Major update to bring in line with the INFO 214 version of the assignment.

nigel.stanger / sqlmarker

Browse code Major update to bring in line with the INFO 214 version of the assignment. master
1 parent 4767018 commit e27a1333978d3d9108632ac627005e069aa9eb43 Nigel Stanger authored on 19 Jul 2013

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<?xml version="1.0" standalone="yes"?> <document class="fragment"> <section label="sec:database-info"> <title>System specification and details</title> <p>The Southern Technical Institute for Natural Knowledge is a medium-sized tertiary education provider (founded in 1982) that teaches papers across many subjects, which lead to several different qualifications. They are currently in the process of designing and implementing a new student records database. The requirements analysis phase of the project is complete, and you have been brought in as a lead database developer. It will be your task to implement an initial prototype of the specification resulting from the requirements analysis phase. An ERD of the proposed database is shown in <hyperlink label="fig:erd"><reference label="fig:erd" /></hyperlink>, and more detailed specifications of the database requirements may be found in the following sections.</p> <figure label="fig:erd" latex-placement="!hb"> <caption>Design-level ERD of the proposed database (Barker notation)</caption> <image basename="STINK_student_records_barker" location="images"> <description>Design-level ERD of the proposed database (Barker notation)</description> </image> </figure> <section label="entity:qualification"> <title>The <tt>Qualification</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Abbreviation</code></cell> <cell>Up to 10 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Full_Name</code></cell> <cell>Up to 100 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Type</code></cell> <cell>(see below)</cell> </row> <row-rule /> </tabular-body> </tabular> <itemised-list> <item>The abbreviation is a short string that identifies the qualification, e.g., “BCom”, “PGDipCApSc” (these are not the only possible values).</item> <item>The qualification type must be one of the following: “Degree”, “Diploma” or “Certificate”.</item> </itemised-list> <answer> <code-block> CREATE TABLE Qualification ( Abbreviation VARCHAR2(10), Full_Name VARCHAR2(100) NOT NULL, Type VARCHAR2(11) NOT NULL CONSTRAINT Qualification_Type_Valid CHECK ( Type IN ( 'Degree', 'Diploma', 'Certificate' ) ), -- CONSTRAINT Qualification_PK PRIMARY KEY ( Abbreviation ) ); </code-block> <p indent="no">If we wanted to allow for additional qualification types in future, we could create a separate <code>Qualification_Type</code> lookup table, with a single column <code>Type</code>. We could then replace the <code>CHECK</code> constraint <code>Qualification_Type_Valid</code> with a foreign key to the lookup table. If we use the existing values, this can even be done without breaking the specification.</p> </answer> </section> <section label="entity:paper"> <title>The <tt>Paper</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Paper_Code</code></cell> <cell>7 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Title</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Description</code></cell> <cell>Up to 500 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Points</code></cell> <cell>Whole number 0–36, default 18</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Period</code></cell> <cell>(see below)</cell> </row> <row-rule /> </tabular-body> </tabular> <vskip size="medium" /> <itemised-list> <item>The paper code comprises a four-letter subject code (e.g., “INFO”) followed by a three digit course number (e.g., “214”).</item> <item>The period of a paper must be one of the following: “SS” (Summer School), “S1” (Semester One), “S2” (Semester Two) or “FY” (Full Year).</item> </itemised-list> <answer> <code-block> CREATE TABLE Paper ( Paper_Code CHAR(7), Title VARCHAR2(50) NOT NULL, Description VARCHAR2(500) NOT NULL, Points NUMBER(2) DEFAULT 18 NOT NULL CONSTRAINT Paper_Points_Range CHECK ( Points BETWEEN 0 AND 36 ), Period CHAR(2) NOT NULL CONSTRAINT Paper_Period_Valid CHECK ( Period IN ( 'S1', 'S2', 'SS', 'FY' ) ), -- CONSTRAINT Paper_PK PRIMARY KEY ( Paper_Code ) ); </code-block> </answer> </section> <section label="entity:schedule"> <title>The <tt>Schedule</tt> entity</title> <p>The <tt>Schedule</tt> entity exists only to associate <tt>Qualification</tt> with <tt>Paper</tt> and thus has no additional attributes beyond its primary key attributes.</p> <answer> <code-block> CREATE TABLE Schedule ( Abbreviation VARCHAR2(10), Paper_Code CHAR(7), -- CONSTRAINT Schedule_PK PRIMARY KEY ( Abbreviation, Paper_Code ), CONSTRAINT Schedule_FK_to_Qualification FOREIGN KEY ( Abbreviation ) REFERENCES Qualification, CONSTRAINT Schedule_FK_to_Paper FOREIGN KEY ( Paper_Code ) REFERENCES Paper ); </code-block> </answer> </section> <section label="entity:people"> <title>The <tt>Person</tt>, <tt>Staff</tt> and <tt>Student</tt> entities</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row> <cell header="yes" columns="3"><tt>Person</tt></cell> </row> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Person_ID</code></cell> <cell>Internally generated 7 digit identifier</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Surname</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Other_Names</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Contact_Phone</code></cell> <cell>(see below)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Contact_Address</code></cell> <cell>Up to 200 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Email</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Username</code></cell> <cell>Up to 10 characters</cell> </row> <row-rule /> <row> <cell columns="3" /> </row> <row> <cell header="yes" columns="3"><tt>Staff</tt></cell> </row> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Staff_ID</code></cell> <cell>7 digit identifier</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Rank</code></cell> <cell>(see below)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Salary</code></cell> <cell>Monetary, <ge /><dollar-sign /><number>40450.00</number></cell> </row> <row-rule /> <row> <cell columns="3" /> </row> <row> <cell header="yes" columns="3"><tt>Student</tt></cell> </row> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Student_ID</code></cell> <cell>7 digit identifier</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Home_Phone</code></cell> <cell>(see below)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Home_Address</code></cell> <cell>Up to 200 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>International</code></cell> <cell>True/false, default false</cell> </row> <row-rule /> </tabular-body> </tabular> <vskip size="medium" /> <itemised-list> <item><tt>Staff</tt> and <tt>Student</tt> are subtypes of <tt>Person</tt>, and thus share the same primary key values.</item> <item>Contact phone numbers must cater for full national landline and mobile numbers. Students’ home phone numbers must cater for full international numbers, as many students are from overseas.</item> <item>A staff member’s rank must be one of the following: “AL” (Assistant Lecturer), “L” (Lecturer), “SL” (Senior Lecturer), “AP” (Associate Professor) or “P” (Professor). Salaries for the highest level positions are over <dollar-sign /><number>100000</number>.</item> </itemised-list> <answer> <code-block> CREATE TABLE Person ( Person_ID NUMBER(7), Surname VARCHAR2(50) NOT NULL, Other_Names VARCHAR2(50) NOT NULL, Contact_Phone VARCHAR2(11), -- at least 11, maybe more Contact_Address VARCHAR2(200) NOT NULL, Username VARCHAR2(50) NOT NULL CONSTRAINT Person_Username_Unique UNIQUE, -- bonus marks! -- CONSTRAINT Person_PK PRIMARY KEY ( Person_ID ) ); CREATE TABLE Staff ( Staff_ID NUMBER(7), Rank VARCHAR2(2) NOT NULL CONSTRAINT Staff Rank_Valid CHECK ( Rank IN ( 'AL', 'L', 'SL', 'AP', 'P' ) ), Salary NUMBER(8,2) NOT NULL CONSTRAINT Staff_Salary_Range CHECK ( Salary >= 40450 ), -- CONSTRAINT Staff_PK PRIMARY KEY ( Staff_ID ), CONSTRAINT Staff_FK_to_Person FOREIGN KEY ( Staff_ID ) REFERENCES Person ( Person_ID ) ); CREATE TABLE Student ( Student_ID NUMBER(7), Home_Phone VARCHAR2(15), -- ITU Recommendation E.164 Home_Address VARCHAR2(200) NOT NULL, International CHAR(1) DEFAULT 'F' NOT NULL CONSTRAINT Student_International_Valid CHECK ( International IN ( 'T', 'F' ) ), Supervisor_ID NUMBER(7), -- optional -- CONSTRAINT Student_PK PRIMARY KEY (Student_ID), CONSTRAINT Student_FK_to_Person FOREIGN KEY (Student_ID) REFERENCES Person (Person_ID), CONSTRAINT Student_FK_to_Staff FOREIGN KEY (Supervisor_ID) REFERENCES Staff (Staff_ID) ); </code-block> <p>It’s important when implementing “boolean” style columns such as <code>International</code> in <code>Student</code> and <code>Release</code> in <code>Assessment</code> that you are consistent in the values that you use across all such columns (more precisely, all such columns should have the same domain). Quite a few people did something like implement one column as <code>'T', 'F'</code> and the other as <code>'True', 'False'</code>, or even more subtle, <code>'t', 'f'</code> (remembering that SQL is case sensitive). Using inconsistent domains for columns that should have the same domain could lead to subtle bugs later on.</p> <p>This of course is really a consequence of not having a proper <code>BOOLEAN</code> data type in SQL. However, one person did discover—possibly inadvertently, given that it isn’t mentioned anywhere in the documentation—that <OracleServer /> now supports the use of the <code>BOOLEAN</code> data type in <code>CREATE TABLE</code>! This certainly wasn’t possible in older versions, where <code>BOOLEAN</code> was available in PL/SQL only.</p> </answer> </section> <section label="entity:teach"> <title>The <tt>Teach</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Staff_ID</code></cell> <cell>7 digit identifier</cell> </row> <row> <cell><tt><hash /></tt></cell> <cell><code>Paper_Code</code></cell> <cell>7 characters</cell> </row> <row> <cell><tt><hash /></tt></cell> <cell><code>Year_Taught</code></cell> <cell>4 digits</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Role</code></cell> <cell>(see below)</cell> </row> <row-rule /> </tabular-body> </tabular> <vskip size="medium" /> <itemised-list> <item>The teaching year cannot be earlier than the year in which the Institute was founded. (Technically it should also not be in the future, but this is surprisingly difficult to check in <OracleServer />! You are welcome to try <em>if you have already completed the rest of the assignment</em>.)</item> <item>The role must be one of the following: “Coordinator”, “Lecturer” or “Tutor”.</item> </itemised-list> <answer> <code-block> CREATE TABLE Teach ( Staff_ID NUMBER(7), Paper_Code CHAR(7), Year_Taught NUMBER(4), CONSTRAINT Teach_Year_Taught_Range CHECK ( Year_Taught >= 1982 ), Role VARCHAR2(11) NOT NULL CONSTRAINT Teach_Role_Valid CHECK ( Role IN ( 'Coordinator', 'Lecturer', 'Tutor' ) ), -- CONSTRAINT Teach_PK PRIMARY KEY ( Staff_ID, Paper_Code, Year_Taught ), CONSTRAINT Teach_FK_to_Staff FOREIGN KEY ( Staff_ID ) REFERENCES Staff, CONSTRAINT Teach_FK_to_Paper FOREIGN KEY ( Paper_Code ) REFERENCES Paper ); </code-block> </answer> </section> <section label="entity:enrolment"> <title>The <tt>Enrolment</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Enrolment_ID</code></cell> <cell>Internally generated 10 digit identifier</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Description</code></cell> <cell>Up to 100 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Year_Enrolled</code></cell> <cell>4 digits</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Comments</code></cell> <cell>Arbitrary text</cell> </row> <row-rule /> </tabular-body> </tabular> <vskip size="medium" /> <itemised-list> <item>The year of enrolment cannot be earlier than the year in which the Institute was founded (nor in the future—see the note above under the <hyperlink label="entity:teach"><tt>Teach</tt><space />entity</hyperlink>).</item> <item>The <tt>Comments</tt> attribute is used to record details of any issues relating to the enrolment, e.g., a detailed explanation of the reasons for waiving a prerequisite, or a description of how a timetable clash is to be resolved.</item> </itemised-list> <answer> <code-block> CREATE TABLE Enrolment ( Enrolment_ID NUMBER(10), Description VARCHAR2(100) NOT NULL, Year_Enrolled NUMBER(4) NOT NULL CONSTRAINT Enrolment_Year_Enrolled_Range CHECK (Year_Enrolled >= 1982), Comments VARCHAR2(4000), -- or CLOB Student_ID NUMBER(7) NOT NULL, Paper_Code CHAR(7) NOT NULL, -- CONSTRAINT Enrolment_PK PRIMARY KEY ( Enrolment_ID ), CONSTRAINT Enrolment_FK_to_Student FOREIGN KEY ( Student_ID ) REFERENCES Student, CONSTRAINT Enrolment_FK_to_Paper FOREIGN KEY ( Paper_Code ) REFERENCES Paper ); </code-block> <p indent="no">A surprising number of people appear to have missed the statement of when the Institute was founded in the first paragraph of the specification!</p> <p>Another very common error was to set the size of the <code>Comments</code> column to a relatively small number, like 200. Think about how much you can say in that many characters (one and a bit text messages), then consider what kinds of things you might want to enter into a general comments column. We deducted marks for anything smaller than 500 characters. When you have no idea of how much you’re going to get, it’s much better to go large than to go small!</p> </answer> </section> <section label="entity:assessment"> <title>The <tt>Assessment</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Assessment_ID</code></cell> <cell>Internally generated 10 digit identifier</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Assessment_Year</code></cell> <cell>4 digits</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Name</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Description</code></cell> <cell>Up to 500 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Type</code></cell> <cell>(see below)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Release</code></cell> <cell>True/false, default false</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Weight</code></cell> <cell>0–100, no decimal places</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Maximum_Mark</code></cell> <cell>(see below)</cell> </row> <row-rule /> </tabular-body> </tabular> <vskip size="medium" /> <itemised-list> <item>A new set of assessments is created for each year that a paper is offered. The year cannot be earlier than the year in which the Institute was founded (nor in the future—see the note above under the <hyperlink label="entity:teach"><tt>Teach</tt><space />entity</hyperlink>).</item> <item>The assessment type must be one of the following: “A” (assignment), “P” (presentation), “T” (test) or “X” (exam).</item> <item>The <code>Maximum_Mark</code> attribute stores the maximum possible raw mark for the assessment (e.g., 30), while the <code>Weight</code> attribute stores the percentage weight of this assessment for the paper as a whole (e.g., 10<percent-sign />). If <code>Maximum_Mark</code> is not specified, then applications should use <code>Weight</code> for both.</item> <item>The <code>Release</code> attribute controls whether or not the marks for this assessment are publicly accessible.</item> </itemised-list> <answer> <code-block> CREATE TABLE Assessment ( Assessment_ID NUMBER(10), Assessment_Year NUMBER(4) NOT NULL CONSTRAINT Assessment_Year_Range CHECK ( Assessment_Year >= 1982 ), Name VARCHAR2(50) NOT NULL, Description VARCHAR2(500), Type CHAR(1) NOT NULL CONSTRAINT Assessment_Type_Valid CHECK ( Type IN ( 'A', 'P', 'T', 'X' ) ), Release CHAR(1) DEFAULT 'F' NOT NULL CONSTRAINT Assessment_Release_Valid CHECK ( Release IN ( 'T', 'F' ) ), Weight NUMBER(3) NOT NULL CONSTRAINT Assessment_Weight_Range CHECK ( Weight BETWEEN 0 AND 100 ), Maximum_Mark NUMBER(3), Paper_Code CHAR(7) NOT NULL, -- CONSTRAINT Assessment_PK PRIMARY KEY ( Assessment_ID ), CONSTRAINT Assessment_FK_to_Paper FOREIGN KEY ( Paper_Code ) REFERENCES Paper ); </code-block> </answer> </section> <section label="entity:result"> <title>The <tt>Result</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Assessment_ID</code></cell> <cell>10 digit identifier</cell> </row> <row> <cell><tt><hash /></tt></cell> <cell><code>Enrolment_ID</code></cell> <cell>10 digit identifier</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Raw_Mark</code></cell> <cell>3 digits plus 1 decimal place (i.e., 000.0)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Weighted_Mark</code></cell> <cell>Floating point</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Percentage_Mark</code></cell> <cell>0–100, 2 decimal places</cell> </row> <row-rule /> </tabular-body> </tabular> <vskip size="medium" /> <itemised-list> <item>The <code>Raw_Mark</code> attribute stores the raw mark awarded for an assessment. Its value should be between zero and the value of <code>Assessment.Maximum_Mark</code> (note that only the former is required for this assignment—bonus marks if you can also achieve the latter).</item> <item>The value of the <code>Weighted_Mark</code> attribute is calculated by the formula: <line-break /> <code>Raw_Mark</code> / <code>Assessment.Maximum_Mark</code><space /> <times /><space /> <code>Assessment.Weight</code>.</item> <item>The value of the <code>Percentage_Mark</code> attribute is calculated by the formula: <line-break /> <code>Raw_Mark</code> / <code>Assessment.Maximum_Mark</code><space /> <times /> 100.</item> <item>Note that the two calculations above are <emph>not</emph> constraints and should not be implemented as such. You may attempt to implement these calculations if you feel confident in your ability to do so, but please ensure that you complete the rest of the assignment <em>first</em>.</item> </itemised-list> <answer> <code-block> CREATE TABLE Result ( Assessment_ID NUMBER(10), Enrolment_ID NUMBER(10), Raw_Mark NUMBER(4,1) NOT NULL, Weighted_Mark NUMBER NOT NULL, Percentage_Mark NUMBER(5,2) NOT NULL CONSTRAINT Result_Percentage_Mark_Range CHECK (Percentage_Mark BETWEEN 0 AND 100), -- CONSTRAINT Result_PK PRIMARY KEY ( Assessment_ID, Enrolment_ID ), CONSTRAINT Result_FK_to_Assessment FOREIGN KEY ( Assessment_ID ) REFERENCES Assessment, CONSTRAINT Result_FK_to_Enrolment FOREIGN KEY ( Enrolment_ID ) REFERENCES Enrolment ); </code-block> <p indent="no">A lot of people got the sizes of the various <code>NUMBER</code> columns incorrect. Remember that the number of decimal places is <em>included</em> in the total number of digits, not <em>in addition to</em>.</p> <p>We also accepted <code>FLOAT</code> and <code>BINARY_FLOAT</code> for <code>Weighted_Mark</code>. Anything with a fixed number of decimal places was marked down, as this is a <em>fixed</em> point number, not a floating point number.</p> </answer> </section> </section> </document> <?xml version="1.0" standalone="yes"?> <document class="fragment"> <section label="sec:database-info"> <title>System specification and details</title> <p>The Southern Technical Institute for Natural Knowledge is a medium-sized tertiary education provider (founded in 1982) that teaches papers across many subjects, which lead to several different qualifications. They are currently in the process of designing and implementing a new student records database. The requirements analysis and conceptual design phases of the project are complete, and you have been brought in as lead database developer. It will be your task to implement an initial prototype of the conceptual specification. A design-level entity-relationship diagram of the proposed database is shown in <hyperlink label="fig:erd"><reference label="fig:erd" /></hyperlink>, and more detailed specifications of the database requirements may be found in the following sections. <strong>Reminder:</strong> In the tables that follow, <quote><tt><hash /></tt></quote> indicates the unique identifier, <quote><tt></tt></quote> indicates that a value is required, and <quote><tt>o</tt></quote> indicates that a value is not required.</p> <figure label="fig:erd" latex-placement="!hb"> <caption>Design-level ERD of the proposed database</caption> <image basename="STINK_student_records" location="images"> <description>Design-level ERD of the proposed database</description> </image> </figure> <section> <title>The <tt>Qualification</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Abbreviation</code></cell> <cell>Up to 10 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Full_Name</code></cell> <cell>Up to 100 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Type</code></cell> <cell>(see below)</cell> </row> <row-rule /> </tabular-body> </tabular> <itemised-list> <item>The abbreviation is a short string that identifies the qualification, e.g., <quote>BCom</quote>, <quote>PGDipCApSc</quote> (these are not the only possible values).</item> <item>The qualification type must be one of the following: <quote>Degree</quote>, <quote>Diploma</quote> or <quote>Certificate</quote>.</item> </itemised-list> <answer> <p indent="no"><strong>Qualification</strong><left-brace /><underline>Abbreviation</underline>, Full<underscore />Name, Type<right-brace /></p> <code-block> CREATE TABLE Qualification ( Abbreviation VARCHAR2(10), Full_Name VARCHAR2(100) NOT NULL, Type VARCHAR2(11) NOT NULL CONSTRAINT Qualification_Type_Valid CHECK (Type IN ('Degree', 'Diploma', 'Certificate')), -- CONSTRAINT Qualification_PK PRIMARY KEY (Abbreviation) ); </code-block> <p indent="no">If we wanted to allow for additional qualification types in future, we could create a separate <code>Qualification_Type</code> lookup table, with a single column <code>Type</code>. We could then replace the <code>CHECK</code> constraint <code>Qualification_Type_Valid</code> with a foreign key to the lookup table. </p> </answer> </section> <section> <title>The <tt>Paper</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Paper_Code</code></cell> <cell>7 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Title</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Description</code></cell> <cell>Up to 500 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Points</code></cell> <cell>Integer 0<endash />36, default 18</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Period</code></cell> <cell>(see below)</cell> </row> <row-rule /> </tabular-body> </tabular> <vskip size="large" /> <p indent="no">The period of a paper must be one of the following: <quote>SS</quote> (Summer School), <quote>S1</quote> (Semester One), <quote>S2</quote> (Semester Two) or <quote>FY</quote> (Full Year).</p> <answer> <p indent="no"><strong>Paper</strong><left-brace /><underline>Paper<underscore />Code</underline>, Title, Description, Points, Period<right-brace /></p> <code-block> CREATE TABLE Paper ( Paper_Code CHAR(7), Title VARCHAR2(50) NOT NULL, Description VARCHAR2(500) NOT NULL, Points NUMBER(2) DEFAULT 18 NOT NULL CONSTRAINT Paper_Points_Range CHECK (Points BETWEEN 0 AND 36), Period CHAR(2) NOT NULL CONSTRAINT Paper_Period_Valid CHECK (Period IN ('S1', 'S2', 'SS', 'FY')), -- CONSTRAINT Paper_PK PRIMARY KEY (Paper_Code) ); </code-block> <p indent="no">We also need to add an associative entity between <strong>Paper</strong> and <strong>Qualification</strong> in order to resolve the many-to-many relationship:</p> <vskip size="small" /> <p indent="no"><strong>Schedule</strong><left-brace/><underline>Abbreviation, Paper<underscore/>Code</underline><right-brace/>; Abbreviation FK to <strong>Qualification</strong>, Paper<underscore/>Code FK to <strong>Paper</strong></p> <code-block> CREATE TABLE Schedule ( Abbreviation VARCHAR2(10), Paper_Code CHAR(7), -- CONSTRAINT Schedule_PK PRIMARY KEY (Abbreviation, Paper_Code), CONSTRAINT Schedule_FK_to_Qualification FOREIGN KEY (Abbreviation) REFERENCES Qualification, CONSTRAINT Schedule_FK_to_Paper FOREIGN KEY (Paper_Code) REFERENCES Paper ); </code-block> </answer> </section> <section> <title>The <tt>Person</tt> entity and its subtypes</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row> <cell header="yes" columns="3"><tt>Person</tt></cell> </row> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Person_ID</code></cell> <cell>Internally generated 7 digit identifier (see below)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Surname</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Other_Names</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Contact_Phone</code></cell> <cell>(see below)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Contact_Address</code></cell> <cell>Up to 200 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Username</code></cell> <cell>Up to 10 characters</cell> </row> <row-rule /> <row> <cell columns="3" /> </row> <row> <cell header="yes" columns="3"><tt>Staff</tt></cell> </row> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt></tt></cell> <cell><code>Email</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Rank</code></cell> <cell>(see below)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Salary</code></cell> <cell>Monetary, <ge /><dollar-sign />35<digitsep />450.00</cell> </row> <row-rule /> <row> <cell columns="3" /> </row> <row> <cell header="yes" columns="3"><tt>Student</tt></cell> </row> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt></tt></cell> <cell><code>Email</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Home_Phone</code></cell> <cell>(see below)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Home_Address</code></cell> <cell>Up to 200 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>International</code></cell> <cell>True/false, default false</cell> </row> <row-rule /> </tabular-body> </tabular> <itemised-list> <item>You are not required to automatically generate the value of the <code>Person_ID</code> attribute, but bonus marks will be awarded if you are able to do so. (This also applies to the <code>Enrolment_ID</code> and <code>Assessment_ID</code> attributes below.)</item> <item>Phone numbers must cater for full international numbers, as many students are from overseas.</item> <item>A staff member<apostrophe />s rank must be one of the following: <quote>AL</quote> (Assistant Lecturer), <quote>L</quote> (Lecturer), <quote>SL</quote> (Senior Lecturer), <quote>AP</quote> (Associate Professor) or <quote>P</quote> (Professor).</item> </itemised-list> <answer> <p indent="no"><strong>Person</strong><left-brace /><underline>Person<underscore />ID</underline>, Surname, Other<underscore />Names, Contact<underscore />Phone, Contact<underscore />Address, Username<right-brace /></p> <vskip size="small" /> <p indent="no"><strong>Staff</strong><left-brace /><underline>Staff<underscore />ID</underline>, Email, Rank, Salary<right-brace />; Staff<underscore />ID FK to <strong>Person</strong></p> <vskip size="small" /> <p indent="no"><strong>Staff</strong><left-brace /><underline>Student<underscore />ID</underline>, Email, Home<underscore />Phone, Home<underscore />Address, International, Supervisor<underscore />ID<right-brace />; Student<underscore />ID FK to <strong>Person</strong>, Supervisor<underscore />ID FK to <strong>Staff</strong></p> <code-block> CREATE TABLE Person ( Person_ID NUMBER(7), Surname VARCHAR2(50) NOT NULL, Other_Names VARCHAR2(50) NOT NULL, Contact_Phone VARCHAR2(12), -- at least 12, maybe more Contact_Address VARCHAR2(200) NOT NULL, Username VARCHAR2(50) NOT NULL CONSTRAINT Person_Username_Unique UNIQUE, -- bonus marks! -- CONSTRAINT Person_PK PRIMARY KEY (Person_ID) ); CREATE TABLE Staff ( Staff_ID NUMBER(7), Email VARCHAR2(50) NOT NULL, Rank VARCHAR2(2) NOT NULL CONSTRAINT Staff Rank_Valid CHECK (Rank IN ('AL', 'L', 'SL', 'AP', 'P')), Salary NUMBER(7,2) NOT NULL CONSTRAINT Staff_Salary_Range CHECK (Salary >= 35450), -- CONSTRAINT Staff_PK PRIMARY KEY (Staff_ID), CONSTRAINT Staff_FK_to_Person FOREIGN KEY (Staff_ID) REFERENCES Person (Person_ID) ); CREATE TABLE Student ( Student_ID NUMBER(7), Email VARCHAR2(50) NOT NULL, Home_Phone VARCHAR2(12), Home_Address VARCHAR2(200) NOT NULL, International CHAR(1) DEFAULT 'F' NOT NULL CONSTRAINT Student_International_Valid CHECK (International IN ('T', 'F')), Supervisor_ID NUMBER(7), -- optional -- CONSTRAINT Student_PK PRIMARY KEY (Student_ID), CONSTRAINT Student_FK_to_Person FOREIGN KEY (Student_ID) REFERENCES Person (Person_ID), CONSTRAINT Student_FK_to_Staff FOREIGN KEY (Supervisor_ID) REFERENCES Staff (Staff_ID) ); </code-block> <p indent="no">This solution uses the discrete approach for transforming subtypes. The additive approach is also feasible (i.e., place the <strong>Person</strong> attributes into both <strong>Staff</strong> and <strong>Student</strong>, and eliminate <strong>Person</strong> entirely). We accepted either approach, but note that the discrete approach has one distinct advantage over the additive approach in this scenario. Consider what happens when someone is both a staff member and a student: we end up duplicating all the <quote>person</quote> data across both tables. This doesn<apostrophe />t occur with the discrete approach. People who didn<apostrophe />t discuss this aspect lost marks.</p> <p>For those who implemented the additive approach, we marked the <quote>person</quote> attributes in <strong>Staff</strong> and <strong>Student</strong> as if they were a separate <strong>Person</strong> entity.</p> <p>The integrated approach was definitely <em>not</em> suitable due to the supervision relationship between <strong>Staff</strong> and <strong>Student</strong> (which, incidentally, many people missed completely), and the mandatory attributes that exist in both <strong>Staff</strong> and <strong>Student</strong>.</p> <p>We also need to add an associative entity between <strong>Paper</strong> and <strong>Staff</strong> in order to resolve the many-to-many relationship:</p> <vskip size="small" /> <p indent="no"><strong>Teach</strong><left-brace /><underline>Staff<underscore />ID, Paper<underscore />Code</underline><right-brace />; Staff<underscore />ID FK to <strong>Staff</strong>, Paper<underscore />Code FK to <strong>Paper</strong></p> <code-block> CREATE TABLE Teach ( Staff_ID NUMBER(7), Paper_Code CHAR(7), -- CONSTRAINT Teach_PK PRIMARY KEY (Staff_ID, Paper_Code), CONSTRAINT Teach_FK_to_Staff FOREIGN KEY (Staff_ID) REFERENCES Staff, CONSTRAINT Teach_FK_to_Paper FOREIGN KEY (Paper_Code) REFERENCES Paper ); </code-block> <p>It<apostrophe />s important when implementing <quote>boolean</quote> style columns such as <code>International</code> in <code>Student</code> and <code>Visible</code> in <code>Assessment</code> that you are consistent in the values that you use across all such columns (more precisely, all such columns should have the same domain). Quite a few people did something like implement one column as <code>'T', 'F'</code> and the other as <code>'True', 'False'</code>, or even more subtle, <code>'t', 'f'</code> (remembering that SQL is case sensitive). Using inconsistent domains for columns that should have the same domain could lead to subtle bugs later on.</p> <p>This of course is really a consequence of not having a proper <code>BOOLEAN</code> data type in SQL. However, one person did discover<emdash />possibly inadvertently, given that it isn<apostrophe />t mentioned anywhere in the documentation<emdash />that <OracleServer /> now supports the use of the <code>BOOLEAN</code> data type in <code>CREATE TABLE</code>! This certainly wasn<apostrophe />t possible in older versions, where <code>BOOLEAN</code> was available in PL/SQL only.</p> </answer> </section> <newpage /> <section> <title>The <tt>Enrolment</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Enrolment_ID</code></cell> <cell>Internally generated 10 digit identifier</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Description</code></cell> <cell>Up to 100 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Year_Enrolled</code></cell> <cell>4 digits</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Comments</code></cell> <cell>Arbitrary text</cell> </row> <row-rule /> </tabular-body> </tabular> <vskip size="large" /> <p indent="no">The year of enrolment cannot be earlier than the year in which the Institute was founded. (Technically it should also not be in the future, but we cannot check this in <OracleServer />.)</p> <answer> <p indent="no"><strong>Enrolment</strong>(<underline>Enrolment<underscore />ID</underline>, Description, Year<underscore />Enrolled, Comments, Paper<underscore />Code, Student<underscore />ID); Paper<underscore />Code FK to <strong>Paper</strong>, Student<underscore />ID FK to <strong>Student</strong></p> <code-block> CREATE TABLE Enrolment ( Enrolment_ID NUMBER(10), Description VARCHAR2(100) NOT NULL, Year_Enrolled NUMBER(4) NOT NULL CONSTRAINT Enrolment_Year_Enrolled_Range CHECK (Year_Enrolled >= 1982), Comments VARCHAR2(4000), -- or CLOB Student_ID NUMBER(7) NOT NULL, Paper_Code CHAR(7) NOT NULL, -- CONSTRAINT Enrolment_PK PRIMARY KEY (Enrolment_ID), CONSTRAINT Enrolment_FK_to_Student FOREIGN KEY (Student_ID) REFERENCES Student, CONSTRAINT Enrolment_FK_to_Paper FOREIGN KEY (Paper_Code) REFERENCES Paper ); </code-block> <p indent="no">A surprising number of people appear to have missed the statement of when the Institute was founded in the first paragraph of the specification!</p> <p>Another very common error was to set the size of the <code>Comments</code> column to a relatively small number, like 200. Think about how much you can say in that many characters (one and a bit text messages), then consider what kinds of things you might want to enter into a general comments column. We deducted marks for anything smaller than 500 characters. When you have no idea of how much you<apostrophe />re going to get, it<apostrophe />s much better to go large than to go small!</p> </answer> </section> <section> <title>The <tt>Assessment</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Assessment_ID</code></cell> <cell>Internally generated 10 digit identifier</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Assessment_Year</code></cell> <cell>4 digits</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Name</code></cell> <cell>Up to 50 characters</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Description</code></cell> <cell>Up to 500 characters</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Type</code></cell> <cell>(see below)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Visible</code></cell> <cell>True/false, default false</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Weight</code></cell> <cell>0<endash />100, no decimal places</cell> </row> <row> <cell><tt>o</tt></cell> <cell><code>Maximum_Mark</code></cell> <cell>(see below)</cell> </row> <row-rule /> </tabular-body> </tabular> <itemised-list> <item>A new set of assessments is created for each year that a paper is offered. The year cannot be earlier than the year in which the Institute was founded. (Technically it should also not be in the future, but we cannot check this in <OracleServer />.)</item> <item>The assessment type must be one of the following: <quote>A</quote> (assignment), <quote>T</quote> (test) or <quote>X</quote> (exam).</item> <item>The <code>Maximum_Mark</code> attribute stores the maximum possible raw mark for the assessment (e.g., 30), while the <code>Weight</code> attribute stores the percentage weight of this assessment for the paper as a whole (e.g., 10<percent-sign />). If <code>Maximum_Mark</code> is not specified, then applications should use <code>Weight</code> for both.</item> <item>The <code>Visible</code> attribute controls whether or not the marks for this assessment are publicly accessible.</item> </itemised-list> <answer> <p indent="no"><strong>Assessment</strong>(<underline>Assessment<underscore />ID</underline>, Assessment<underscore />Year, Name, Description, Type, Visible, Weight, Maximum<underscore />Mark, Paper<underscore />Code); Paper<underscore />Code FK to <strong>Paper</strong></p> <code-block> CREATE TABLE Assessment ( Assessment_ID NUMBER(10), Assessment_Year NUMBER(4) NOT NULL CONSTRAINT Assessment_Year_Range CHECK (Assessment_Year >= 1982), Name VARCHAR2(50) NOT NULL, Description VARCHAR2(500), Type CHAR(1) NOT NULL CONSTRAINT Assessment_Type_Valid CHECK (Type IN ('A', 'T', 'X')), Visible CHAR(1) DEFAULT 'F' NOT NULL CONSTRAINT Assessment_Visible_Valid CHECK (Visible IN ('T', 'F')), Weight NUMBER(3) NOT NULL CONSTRAINT Assessment_Weight_Range CHECK (Weight BETWEEN 0 AND 100), Maximum_Mark NUMBER(3), Paper_Code CHAR(7) NOT NULL, -- CONSTRAINT Assessment_PK PRIMARY KEY (Assessment_ID), CONSTRAINT Assessment_FK_to_Paper FOREIGN KEY (Paper_Code) REFERENCES Paper ); </code-block> </answer> </section> <newpage /> <section> <title>The <tt>Result</tt> entity</title> <tabular border="1"> <tabular-columns> <column align="center" left-border="\|" right-border="\|" /> <column align="left" right-border="\|" /> <column align="left" right-border="\|" /> </tabular-columns> <tabular-body> <row-rule /> <row> <cell header="yes" /> <cell header="yes">Column</cell> <cell header="yes">Description</cell> </row> <row-rule /> <row> <cell><tt><hash /></tt></cell> <cell><code>Assessment_ID</code></cell> <cell>10 digit identifier</cell> </row> <row> <cell><tt><hash /></tt></cell> <cell><code>Enrolment_ID</code></cell> <cell>10 digit identifier</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Raw_Mark</code></cell> <cell>3 digits plus 1 decimal place (i.e., 000.0)</cell> </row> <row> <cell><tt></tt></cell> <cell><code>Weighted_Mark</code></cell> <cell>Floating point</cell> </row> <row> <cell><tt>*</tt></cell> <cell><code>Percentage_Mark</code></cell> <cell>0<endash />100, 2 decimal places</cell> </row> <row-rule /> </tabular-body> </tabular> <itemised-list> <item>The <code>Raw_Mark</code> attribute stores the raw mark awarded for an assessment. Its value should be between zero and the value of <code>Assessment.Maximum_Mark</code> (note that only the former is required for this assignment<emdash />bonus marks if you can also achieve the latter).</item> <item>The value of the <code>Weighted_Mark</code> attribute is calculated by the formula: <line-break /> <code>Raw_Mark</code> / <code>Assessment.Maximum_Mark</code><space /> <times /><space /> <code>Assessment.Weight</code>.</item> <item>The value of the <code>Percentage_Mark</code> attribute is calculated by the formula: <line-break /> <code>Raw_Mark</code> / <code>Assessment.Maximum_Mark</code><space /> <times /> 100.</item> <item>Note that the two calculations above are <emph>not</emph> constraints and should not be implemented as such. You may attempt to implement these calculations if you feel confident in your ability to do so, but please ensure that you complete the rest of the assignment <em>first</em>.</item> </itemised-list> <answer> <p indent="no"><strong>Result</strong>(<underline>Assessment<underscore />ID, Enrolment<underscore />ID</underline>, Raw<underscore />Mark, Weighted<underscore />Mark, Percentage<underscore />Mark); Assessment<underscore />ID FK to <strong>Assessment</strong>, Enrolment<underscore />ID FK to <strong>Enrolment</strong></p> <code-block> CREATE TABLE Result ( Assessment_ID NUMBER(10), Enrolment_ID NUMBER(10), Raw_Mark NUMBER(4,1) NOT NULL, Weighted_Mark NUMBER NOT NULL, Percentage_Mark NUMBER(5,2) NOT NULL CONSTRAINT Result_Percentage_Mark_Range CHECK (Percentage_Mark BETWEEN 0 AND 100), -- CONSTRAINT Result_PK PRIMARY KEY (Assessment_ID, Enrolment_ID), CONSTRAINT Result_FK_to_Assessment FOREIGN KEY (Assessment_ID) REFERENCES Assessment, CONSTRAINT Result_FK_to_Enrolment FOREIGN KEY (Enrolment_ID) REFERENCES Enrolment ); </code-block> <p indent="no">A lot of people got the sizes of the various <code>NUMBER</code> columns incorrect. Remember that the number of decimal places is <em>included</em> in the total number of digits, not <em>in addition to</em>.</p> <p>We also accepted <code>FLOAT</code> and <code>BINARY_FLOAT</code> for <code>Weighted_Mark</code>. Anything with a fixed number of decimal places was marked down, as this is a <em>fixed</em> point number, not a floating point number.</p> </answer> </section> </section> </document>

Ignore Space Show notes View

STINK_student_records.xml

<?xml version="1.0" standalone="yes"?>

<title>System specification and details</title>

The Southern Technical Institute for Natural Knowledge is a medium-sized tertiary education provider (founded in 1982) that teaches papers across many subjects, which lead to several different qualifications. They are currently in the process of designing and implementing a new student records database. The requirements analysis phase of the project is complete, and you have been brought in as a lead database developer. It will be your task to implement an initial prototype of the specification resulting from the requirements analysis phase. An ERD of the proposed database is shown in <hyperlink label="fig:erd"><reference label="fig:erd" /></hyperlink>, and more detailed specifications of the database requirements may be found in the following sections.

<figure label="fig:erd" latex-placement="!hb">
			<caption>Design-level ERD of the proposed database (Barker notation)</caption>
			<image basename="STINK_student_records_barker" location="images">
				<description>Design-level ERD of the proposed database (Barker notation)</description>
			</image>
		</figure>

<section label="entity:qualification">
		
			<title>The <tt>Qualification</tt> entity</title>

<itemised-list>

<item>The abbreviation is a short string that identifies the qualification, e.g., “BCom”, “PGDipCApSc” (these are not the only possible values).</item>
			
				<item>The qualification type must be one of the following: “Degree”, “Diploma” or “Certificate”.</item>
				
			</itemised-list>
			
			<answer>
			
				<code-block>
CREATE TABLE Qualification
( Abbreviation VARCHAR2(10),
 Full_Name VARCHAR2(100) NOT NULL,
 Type VARCHAR2(11) NOT NULL
 CONSTRAINT Qualification_Type_Valid 
 CHECK ( Type IN ( 'Degree', 'Diploma', 'Certificate' ) ),
 --
 CONSTRAINT Qualification_PK PRIMARY KEY ( Abbreviation )
);
				</code-block>
				
				If we wanted to allow for additional qualification types in future, we could create a separate <code>Qualification_Type</code> lookup table, with a single column <code>Type</code>. We could then replace the <code>CHECK</code> constraint <code>Qualification_Type_Valid</code> with a foreign key to the lookup table. If we use the existing values, this can even be done without breaking the specification.
			
			</answer>
			
		</section>

<section label="entity:paper">
		
			<title>The <tt>Paper</tt> entity</title>

<tabular border="1">
				<tabular-columns>
					<column align="center" left-border="|" right-border="|" />
					<column align="left" right-border="|" />
					<column align="left" right-border="|" />
				</tabular-columns>
				<tabular-body>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Paper_Code</code></cell>
						<cell>7 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Title</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Description</code></cell>
						<cell>Up to 500 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Points</code></cell>
						<cell>Whole number 0–36, default 18</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Period</code></cell>
						<cell>(see below)</cell>
					</row>
					<row-rule />
				</tabular-body>
			</tabular>

<vskip size="medium" />
			
			<itemised-list>
			
				<item>The paper code comprises a four-letter subject code (e.g., “INFO”) followed by a three digit course number (e.g., “214”).</item>
			
				<item>The period of a paper must be one of the following: “SS” (Summer School), “S1” (Semester One), “S2” (Semester Two) or “FY” (Full Year).</item>
			
			</itemised-list>
				
			<answer>
			
				<code-block>
CREATE TABLE Paper
( Paper_Code CHAR(7),
 Title VARCHAR2(50) NOT NULL,
 Description VARCHAR2(500) NOT NULL,
 Points NUMBER(2) DEFAULT 18 NOT NULL
 CONSTRAINT Paper_Points_Range CHECK ( Points BETWEEN 0 AND 36 ),
 Period CHAR(2) NOT NULL
 CONSTRAINT Paper_Period_Valid
 CHECK ( Period IN ( 'S1', 'S2', 'SS', 'FY' ) ),
 --
 CONSTRAINT Paper_PK PRIMARY KEY ( Paper_Code )
);
				</code-block>
			
			</answer>
			
		</section>

<section label="entity:schedule">
		
			<title>The <tt>Schedule</tt> entity</title>

The <tt>Schedule</tt> entity exists only to associate <tt>Qualification</tt> with <tt>Paper</tt> and thus has no additional attributes beyond its primary key attributes.
			
			<answer>
			
				<code-block>
CREATE TABLE Schedule
( Abbreviation VARCHAR2(10),
 Paper_Code CHAR(7),
 --
 CONSTRAINT Schedule_PK PRIMARY KEY ( Abbreviation, Paper_Code ),
 CONSTRAINT Schedule_FK_to_Qualification
 FOREIGN KEY ( Abbreviation ) REFERENCES Qualification,
 CONSTRAINT Schedule_FK_to_Paper FOREIGN KEY ( Paper_Code ) REFERENCES Paper
);
				</code-block>
			
			</answer>
			
		</section>

<section label="entity:people">
		
			<title>The <tt>Person</tt>, <tt>Staff</tt> and <tt>Student</tt> entities</title>

<tabular border="1">
				<tabular-columns>
					<column align="center" left-border="|" right-border="|" />
					<column align="left" right-border="|" />
					<column align="left" right-border="|" />
				</tabular-columns>
				<tabular-body>
					<row>
						<cell header="yes" columns="3"><tt>Person</tt></cell>
					</row>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Person_ID</code></cell>
						<cell>Internally generated 7 digit identifier</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Surname</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Other_Names</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>o</tt></cell>
						<cell><code>Contact_Phone</code></cell>
						<cell>(see below)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Contact_Address</code></cell>
						<cell>Up to 200 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Email</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Username</code></cell>
						<cell>Up to 10 characters</cell>
					</row>
					<row-rule />
					<row>
						<cell columns="3" />
					</row>

<row>
						<cell header="yes" columns="3"><tt>Staff</tt></cell>
					</row>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Staff_ID</code></cell>
						<cell>7 digit identifier</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Rank</code></cell>
						<cell>(see below)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Salary</code></cell>
						<cell>Monetary, <ge /><dollar-sign /><number>40450.00</number></cell>
					</row>
					<row-rule />
					<row>
						<cell columns="3" />
					</row>

<row>
						<cell header="yes" columns="3"><tt>Student</tt></cell>
					</row>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Student_ID</code></cell>
						<cell>7 digit identifier</cell>
					</row>
					<row>
						<cell><tt>o</tt></cell>
						<cell><code>Home_Phone</code></cell>
						<cell>(see below)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Home_Address</code></cell>
						<cell>Up to 200 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>International</code></cell>
						<cell>True/false, default false</cell>
					</row>
					<row-rule />
				</tabular-body>
			</tabular>

<vskip size="medium" />
			
			<itemised-list>
			
				<item><tt>Staff</tt> and <tt>Student</tt> are subtypes of <tt>Person</tt>, and thus share the same primary key values.</item>
				
				<item>Contact phone numbers must cater for full national landline and mobile numbers. Students’ home phone numbers must cater for full international numbers, as many students are from overseas.</item>
				
				<item>A staff member’s rank must be one of the following: “AL” (Assistant Lecturer), “L” (Lecturer), “SL” (Senior Lecturer), “AP” (Associate Professor) or “P” (Professor). Salaries for the highest level positions are over <dollar-sign /><number>100000</number>.</item>
				
			</itemised-list>

<answer>
			
				<code-block>
CREATE TABLE Person
( Person_ID NUMBER(7),
 Surname VARCHAR2(50) NOT NULL,
 Other_Names VARCHAR2(50) NOT NULL,
 Contact_Phone VARCHAR2(11), -- at least 11, maybe more 
 Contact_Address VARCHAR2(200) NOT NULL,
 Username VARCHAR2(50) NOT NULL
 CONSTRAINT Person_Username_Unique UNIQUE, -- bonus marks!
 --
 CONSTRAINT Person_PK PRIMARY KEY ( Person_ID )
);

CREATE TABLE Staff
( Staff_ID          NUMBER(7),
  Rank              VARCHAR2(2)     NOT NULL
    CONSTRAINT Staff Rank_Valid
      CHECK ( Rank IN ( 'AL', 'L', 'SL', 'AP', 'P' ) ),
  Salary            NUMBER(8,2)     NOT NULL
    CONSTRAINT Staff_Salary_Range CHECK ( Salary >= 40450 ),
  --
  CONSTRAINT Staff_PK PRIMARY KEY ( Staff_ID ),
  CONSTRAINT Staff_FK_to_Person
    FOREIGN KEY ( Staff_ID ) REFERENCES Person ( Person_ID )
);

CREATE TABLE Student
( Student_ID NUMBER(7),
 Home_Phone VARCHAR2(15), -- ITU Recommendation E.164
 Home_Address VARCHAR2(200) NOT NULL,
 International CHAR(1) DEFAULT 'F' NOT NULL
 CONSTRAINT Student_International_Valid
 CHECK ( International IN ( 'T', 'F' ) ),
 Supervisor_ID NUMBER(7), -- optional
 --
 CONSTRAINT Student_PK PRIMARY KEY (Student_ID),
 CONSTRAINT Student_FK_to_Person
 FOREIGN KEY (Student_ID) REFERENCES Person (Person_ID),
 CONSTRAINT Student_FK_to_Staff
 FOREIGN KEY (Supervisor_ID) REFERENCES Staff (Staff_ID)
);
				</code-block>
			
				It’s important when implementing “boolean” style columns such as <code>International</code> in <code>Student</code> and <code>Release</code> in <code>Assessment</code> that you are consistent in the values that you use across all such columns (more precisely, all such columns should have the same domain). Quite a few people did something like implement one column as <code>'T', 'F'</code> and the other as <code>'True', 'False'</code>, or even more subtle, <code>'t', 'f'</code> (remembering that SQL is case sensitive). Using inconsistent domains for columns that should have the same domain could lead to subtle bugs later on.
				
				This of course is really a consequence of not having a proper <code>BOOLEAN</code> data type in SQL. However, one person did discover—possibly inadvertently, given that it isn’t mentioned anywhere in the documentation—that <OracleServer /> now supports the use of the <code>BOOLEAN</code> data type in <code>CREATE TABLE</code>! This certainly wasn’t possible in older versions, where <code>BOOLEAN</code> was available in PL/SQL only.

</answer>
			
		</section>
		
		
		<section label="entity:teach">
		
			<title>The <tt>Teach</tt> entity</title>

<vskip size="medium" />
			
			<itemised-list>
			
				<item>The teaching year cannot be earlier than the year in which the Institute was founded. (Technically it should also not be in the future, but this is surprisingly difficult to check in <OracleServer />! You are welcome to try if you have already completed the rest of the assignment.)</item>

<item>The role must be one of the following: “Coordinator”, “Lecturer” or “Tutor”.</item>
				
			</itemised-list>

<answer>
			
				<code-block>
CREATE TABLE Teach
( Staff_ID NUMBER(7),
 Paper_Code CHAR(7),
 Year_Taught NUMBER(4),
 CONSTRAINT Teach_Year_Taught_Range CHECK ( Year_Taught >= 1982 ),
 Role VARCHAR2(11) NOT NULL
 CONSTRAINT Teach_Role_Valid
 CHECK ( Role IN ( 'Coordinator', 'Lecturer', 'Tutor' ) ),
 --
 CONSTRAINT Teach_PK PRIMARY KEY ( Staff_ID, Paper_Code, Year_Taught ),
 CONSTRAINT Teach_FK_to_Staff FOREIGN KEY ( Staff_ID ) REFERENCES Staff,
 CONSTRAINT Teach_FK_to_Paper FOREIGN KEY ( Paper_Code ) REFERENCES Paper
);
				</code-block>

</answer>
			
		</section>
		
		
		<section label="entity:enrolment">
		
			<title>The <tt>Enrolment</tt> entity</title>

<vskip size="medium" />
			
			<itemised-list>
			
				<item>The year of enrolment cannot be earlier than the year in which the Institute was founded (nor in the future—see the note above under the <hyperlink label="entity:teach"><tt>Teach</tt><space />entity</hyperlink>).</item>
			
				<item>The <tt>Comments</tt> attribute is used to record details of any issues relating to the enrolment, e.g., a detailed explanation of the reasons for waiving a prerequisite, or a description of how a timetable clash is to be resolved.</item>
			
			</itemised-list>
				
			<answer>
			
				<code-block>
CREATE TABLE Enrolment
( Enrolment_ID NUMBER(10),
 Description VARCHAR2(100) NOT NULL,
 Year_Enrolled NUMBER(4) NOT NULL
 CONSTRAINT Enrolment_Year_Enrolled_Range
 CHECK (Year_Enrolled >= 1982),
 Comments VARCHAR2(4000), -- or CLOB
 Student_ID NUMBER(7) NOT NULL,
 Paper_Code CHAR(7) NOT NULL,
 --
 CONSTRAINT Enrolment_PK PRIMARY KEY ( Enrolment_ID ),
 CONSTRAINT Enrolment_FK_to_Student
 FOREIGN KEY ( Student_ID ) REFERENCES Student,
 CONSTRAINT Enrolment_FK_to_Paper
 FOREIGN KEY ( Paper_Code ) REFERENCES Paper
);
				</code-block>
				
				A surprising number of people appear to have missed the statement of when the Institute was founded in the first paragraph of the specification!
				
				Another very common error was to set the size of the <code>Comments</code> column to a relatively small number, like 200. Think about how much you can say in that many characters (one and a bit text messages), then consider what kinds of things you might want to enter into a general comments column. We deducted marks for anything smaller than 500 characters. When you have no idea of how much you’re going to get, it’s much better to go large than to go small!
			
			</answer>
			
		</section>

<section label="entity:assessment">
		
			<title>The <tt>Assessment</tt> entity</title>

<tabular border="1">
				<tabular-columns>
					<column align="center" left-border="|" right-border="|" />
					<column align="left" right-border="|" />
					<column align="left" right-border="|" />
				</tabular-columns>
				<tabular-body>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Assessment_ID</code></cell>
						<cell>Internally generated 10 digit identifier</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Assessment_Year</code></cell>
						<cell>4 digits</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Name</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>o</tt></cell>
						<cell><code>Description</code></cell>
						<cell>Up to 500 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Type</code></cell>
						<cell>(see below)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Release</code></cell>
						<cell>True/false, default false</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Weight</code></cell>
						<cell>0–100, no decimal places</cell>
					</row>
					<row>
						<cell><tt>o</tt></cell>
						<cell><code>Maximum_Mark</code></cell>
						<cell>(see below)</cell>
					</row>
					<row-rule />
				</tabular-body>
			</tabular>

<vskip size="medium" />
			
			<itemised-list>
			
				<item>A new set of assessments is created for each year that a paper is offered. The year cannot be earlier than the year in which the Institute was founded (nor in the future—see the note above under the <hyperlink label="entity:teach"><tt>Teach</tt><space />entity</hyperlink>).</item>
				
				<item>The assessment type must be one of the following: “A” (assignment), “P” (presentation), “T” (test) or “X” (exam).</item>
				
				<item>The <code>Maximum_Mark</code> attribute stores the maximum possible raw mark for the assessment (e.g., 30), while the <code>Weight</code> attribute stores the percentage weight of this assessment for the paper as a whole (e.g., 10<percent-sign />). If <code>Maximum_Mark</code> is not specified, then applications should use <code>Weight</code> for both.</item>
				
				<item>The <code>Release</code> attribute controls whether or not the marks for this assessment are publicly accessible.</item>
				
			</itemised-list>
			
			<answer>
			
				<code-block>
CREATE TABLE Assessment
( Assessment_ID NUMBER(10),
 Assessment_Year NUMBER(4) NOT NULL
 CONSTRAINT Assessment_Year_Range
 CHECK ( Assessment_Year >= 1982 ),
 Name VARCHAR2(50) NOT NULL,
 Description VARCHAR2(500),
 Type CHAR(1) NOT NULL
 CONSTRAINT Assessment_Type_Valid
 CHECK ( Type IN ( 'A', 'P', 'T', 'X' ) ),
 Release CHAR(1) DEFAULT 'F' NOT NULL
 CONSTRAINT Assessment_Release_Valid CHECK ( Release IN ( 'T', 'F' ) ),
 Weight NUMBER(3) NOT NULL
 CONSTRAINT Assessment_Weight_Range CHECK ( Weight BETWEEN 0 AND 100 ),
 Maximum_Mark NUMBER(3),
 Paper_Code CHAR(7) NOT NULL,
 --
 CONSTRAINT Assessment_PK PRIMARY KEY ( Assessment_ID ),
 CONSTRAINT Assessment_FK_to_Paper
 FOREIGN KEY ( Paper_Code ) REFERENCES Paper
);
				</code-block>
				
			</answer>
			
		</section>
		
		
		<section label="entity:result">
		
			<title>The <tt>Result</tt> entity</title>

<tabular border="1">
				<tabular-columns>
					<column align="center" left-border="|" right-border="|" />
					<column align="left" right-border="|" />
					<column align="left" right-border="|" />
				</tabular-columns>
				<tabular-body>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Assessment_ID</code></cell>
						<cell>10 digit identifier</cell>
					</row>
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Enrolment_ID</code></cell>
						<cell>10 digit identifier</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Raw_Mark</code></cell>
						<cell>3 digits plus 1 decimal place (i.e., 000.0)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Weighted_Mark</code></cell>
						<cell>Floating point</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Percentage_Mark</code></cell>
						<cell>0–100, 2 decimal places</cell>
					</row>
					<row-rule />
				</tabular-body>
			</tabular>

<vskip size="medium" />
			
			<itemised-list>
			
				<item>The <code>Raw_Mark</code> attribute stores the raw mark awarded for an assessment. Its value should be between zero and the value of <code>Assessment.Maximum_Mark</code> (note that only the former is required for this assignment—bonus marks if you can also achieve the latter).</item>
				
				<item>The value of the <code>Weighted_Mark</code> attribute is calculated by the formula: <line-break />
				<code>Raw_Mark</code> / <code>Assessment.Maximum_Mark</code><space /> <times /><space /> <code>Assessment.Weight</code>.</item>
				
				<item>The value of the <code>Percentage_Mark</code> attribute is calculated by the formula: <line-break />
				<code>Raw_Mark</code> / <code>Assessment.Maximum_Mark</code><space /> <times /> 100.</item>
				
				<item>Note that the two calculations above are <emph>not</emph> constraints and should not be implemented as such. You may attempt to implement these calculations if you feel confident in your ability to do so, but please ensure that you complete the rest of the assignment first.</item>
				
			</itemised-list>
			
			<answer>
			
				<code-block>
CREATE TABLE Result
( Assessment_ID NUMBER(10),
 Enrolment_ID NUMBER(10),
 Raw_Mark NUMBER(4,1) NOT NULL,
 Weighted_Mark NUMBER NOT NULL,
 Percentage_Mark NUMBER(5,2) NOT NULL
 CONSTRAINT Result_Percentage_Mark_Range
 CHECK (Percentage_Mark BETWEEN 0 AND 100),
 --
 CONSTRAINT Result_PK PRIMARY KEY ( Assessment_ID, Enrolment_ID ),
 CONSTRAINT Result_FK_to_Assessment
 FOREIGN KEY ( Assessment_ID ) REFERENCES Assessment,
 CONSTRAINT Result_FK_to_Enrolment
 FOREIGN KEY ( Enrolment_ID ) REFERENCES Enrolment
);
				</code-block>
				
				A lot of people got the sizes of the various <code>NUMBER</code> columns incorrect. Remember that the number of decimal places is included in the total number of digits, not in addition to.
				
				We also accepted <code>FLOAT</code> and <code>BINARY_FLOAT</code> for <code>Weighted_Mark</code>. Anything with a fixed number of decimal places was marked down, as this is a fixed point number, not a floating point number.
				
			</answer>
			
		</section>
	
	</section>

</document>

<?xml version="1.0" standalone="yes"?>

<title>System specification and details</title>

The Southern Technical Institute for Natural Knowledge is a medium-sized tertiary education provider (founded in 1982) that teaches papers across many subjects, which lead to several different qualifications. They are currently in the process of designing and implementing a new student records database. The requirements analysis and conceptual design phases of the project are complete, and you have been brought in as lead database developer. It will be your task to implement an initial prototype of the conceptual specification. A design-level entity-relationship diagram of the proposed database is shown in <hyperlink label="fig:erd"><reference label="fig:erd" /></hyperlink>, and more detailed specifications of the database requirements may be found in the following sections. Reminder: In the tables that follow, <quote><tt><hash /></tt></quote> indicates the unique identifier, <quote><tt>*</tt></quote> indicates that a value is required, and <quote><tt>o</tt></quote> indicates that a value is not required.

<figure label="fig:erd" latex-placement="!hb">
			<caption>Design-level ERD of the proposed database</caption>
			<image basename="STINK_student_records" location="images">
				<description>Design-level ERD of the proposed database</description>
			</image>
		</figure>

<section>
		
			<title>The <tt>Qualification</tt> entity</title>

<itemised-list>

<item>The abbreviation is a short string that identifies the qualification, e.g., <quote>BCom</quote>, <quote>PGDipCApSc</quote> (these are not the only possible values).</item>
			
				<item>The qualification type must be one of the following: <quote>Degree</quote>, <quote>Diploma</quote> or <quote>Certificate</quote>.</item>
				
			</itemised-list>
			
			<answer>
			
				Qualification<left-brace /><underline>Abbreviation</underline>, Full<underscore />Name, Type<right-brace />
				
				<code-block>
CREATE TABLE Qualification
( Abbreviation VARCHAR2(10),
 Full_Name VARCHAR2(100) NOT NULL,
 Type VARCHAR2(11) NOT NULL
 CONSTRAINT Qualification_Type_Valid 
 CHECK (Type IN ('Degree', 'Diploma', 'Certificate')),
 --
 CONSTRAINT Qualification_PK PRIMARY KEY (Abbreviation)
);
				</code-block>
				
				If we wanted to allow for additional qualification types in future, we could create a separate <code>Qualification_Type</code> lookup table, with a single column <code>Type</code>. We could then replace the <code>CHECK</code> constraint <code>Qualification_Type_Valid</code> with a foreign key to the lookup table. 
			
			</answer>
			
		</section>

<section>
		
			<title>The <tt>Paper</tt> entity</title>

<tabular border="1">
				<tabular-columns>
					<column align="center" left-border="|" right-border="|" />
					<column align="left" right-border="|" />
					<column align="left" right-border="|" />
				</tabular-columns>
				<tabular-body>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Paper_Code</code></cell>
						<cell>7 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Title</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Description</code></cell>
						<cell>Up to 500 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Points</code></cell>
						<cell>Integer 0<endash />36, default 18</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Period</code></cell>
						<cell>(see below)</cell>
					</row>
					<row-rule />
				</tabular-body>
			</tabular>

<vskip size="large" />
			
			The period of a paper must be one of the following: <quote>SS</quote> (Summer School), <quote>S1</quote> (Semester One), <quote>S2</quote> (Semester Two) or <quote>FY</quote> (Full Year).
				
			<answer>
			
				Paper<left-brace /><underline>Paper<underscore />Code</underline>, Title, Description, Points, Period<right-brace />
				
				<code-block>
CREATE TABLE Paper
( Paper_Code CHAR(7),
 Title VARCHAR2(50) NOT NULL,
 Description VARCHAR2(500) NOT NULL,
 Points NUMBER(2) DEFAULT 18 NOT NULL
 CONSTRAINT Paper_Points_Range CHECK (Points BETWEEN 0 AND 36),
 Period CHAR(2) NOT NULL
 CONSTRAINT Paper_Period_Valid
 CHECK (Period IN ('S1', 'S2', 'SS', 'FY')),
 --
 CONSTRAINT Paper_PK PRIMARY KEY (Paper_Code)
);
				</code-block>
			
				We also need to add an associative entity between Paper and Qualification in order to resolve the many-to-many relationship:
				
				<vskip size="small" />
				
				Schedule<left-brace/><underline>Abbreviation, Paper<underscore/>Code</underline><right-brace/>; Abbreviation FK to Qualification, Paper<underscore/>Code FK to Paper
				
				<code-block>
CREATE TABLE Schedule
( Abbreviation VARCHAR2(10),
 Paper_Code CHAR(7),
 --
 CONSTRAINT Schedule_PK PRIMARY KEY (Abbreviation, Paper_Code),
 CONSTRAINT Schedule_FK_to_Qualification
 FOREIGN KEY (Abbreviation) REFERENCES Qualification,
 CONSTRAINT Schedule_FK_to_Paper FOREIGN KEY (Paper_Code) REFERENCES Paper
);
				</code-block>

</answer>
			
		</section>

<section>
		
			<title>The <tt>Person</tt> entity and its subtypes</title>

<tabular border="1">
				<tabular-columns>
					<column align="center" left-border="|" right-border="|" />
					<column align="left" right-border="|" />
					<column align="left" right-border="|" />
				</tabular-columns>
				<tabular-body>
					<row>
						<cell header="yes" columns="3"><tt>Person</tt></cell>
					</row>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Person_ID</code></cell>
						<cell>Internally generated 7 digit identifier (see below)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Surname</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Other_Names</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>o</tt></cell>
						<cell><code>Contact_Phone</code></cell>
						<cell>(see below)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Contact_Address</code></cell>
						<cell>Up to 200 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Username</code></cell>
						<cell>Up to 10 characters</cell>
					</row>
					<row-rule />
					<row>
						<cell columns="3" />
					</row>

<row>
						<cell header="yes" columns="3"><tt>Staff</tt></cell>
					</row>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Email</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Rank</code></cell>
						<cell>(see below)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Salary</code></cell>
						<cell>Monetary, <ge /><dollar-sign />35<digitsep />450.00</cell>
					</row>
					<row-rule />
					<row>
						<cell columns="3" />
					</row>

<row>
						<cell header="yes" columns="3"><tt>Student</tt></cell>
					</row>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Email</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>o</tt></cell>
						<cell><code>Home_Phone</code></cell>
						<cell>(see below)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Home_Address</code></cell>
						<cell>Up to 200 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>International</code></cell>
						<cell>True/false, default false</cell>
					</row>
					<row-rule />
				</tabular-body>
			</tabular>

<itemised-list>
			
				<item>You are not required to automatically generate the value of the <code>Person_ID</code> attribute, but bonus marks will be awarded if you are able to do so. (This also applies to the <code>Enrolment_ID</code> and <code>Assessment_ID</code> attributes below.)</item>
			
				<item>Phone numbers must cater for full international numbers, as many students are from overseas.</item>
				
				<item>A staff member<apostrophe />s rank must be one of the following: <quote>AL</quote> (Assistant Lecturer), <quote>L</quote> (Lecturer), <quote>SL</quote> (Senior Lecturer), <quote>AP</quote> (Associate Professor) or <quote>P</quote> (Professor).</item>
				
			</itemised-list>

<answer>
			
				Person<left-brace /><underline>Person<underscore />ID</underline>, Surname, Other<underscore />Names, Contact<underscore />Phone, Contact<underscore />Address, Username<right-brace />
				
				<vskip size="small" />
			
				Staff<left-brace /><underline>Staff<underscore />ID</underline>, Email, Rank, Salary<right-brace />; Staff<underscore />ID FK to Person
			
				<vskip size="small" />
			
				Staff<left-brace /><underline>Student<underscore />ID</underline>, Email, Home<underscore />Phone, Home<underscore />Address, International, Supervisor<underscore />ID<right-brace />; Student<underscore />ID FK to Person, Supervisor<underscore />ID FK to Staff
				
				<code-block>
CREATE TABLE Person
( Person_ID NUMBER(7),
 Surname VARCHAR2(50) NOT NULL,
 Other_Names VARCHAR2(50) NOT NULL,
 Contact_Phone VARCHAR2(12), -- at least 12, maybe more 
 Contact_Address VARCHAR2(200) NOT NULL,
 Username VARCHAR2(50) NOT NULL
 CONSTRAINT Person_Username_Unique UNIQUE, -- bonus marks!
 --
 CONSTRAINT Person_PK PRIMARY KEY (Person_ID)
);

CREATE TABLE Staff
( Staff_ID          NUMBER(7),
  Email             VARCHAR2(50)    NOT NULL,
  Rank              VARCHAR2(2)     NOT NULL
    CONSTRAINT Staff Rank_Valid
      CHECK (Rank IN ('AL', 'L', 'SL', 'AP', 'P')),
  Salary            NUMBER(7,2)     NOT NULL
    CONSTRAINT Staff_Salary_Range CHECK (Salary >= 35450),
  --
  CONSTRAINT Staff_PK PRIMARY KEY (Staff_ID),
  CONSTRAINT Staff_FK_to_Person
    FOREIGN KEY (Staff_ID) REFERENCES Person (Person_ID)
);

CREATE TABLE Student
( Student_ID NUMBER(7),
 Email VARCHAR2(50) NOT NULL,
 Home_Phone VARCHAR2(12),
 Home_Address VARCHAR2(200) NOT NULL,
 International CHAR(1) DEFAULT 'F' NOT NULL
 CONSTRAINT Student_International_Valid
 CHECK (International IN ('T', 'F')),
 Supervisor_ID NUMBER(7), -- optional
 --
 CONSTRAINT Student_PK PRIMARY KEY (Student_ID),
 CONSTRAINT Student_FK_to_Person
 FOREIGN KEY (Student_ID) REFERENCES Person (Person_ID),
 CONSTRAINT Student_FK_to_Staff
 FOREIGN KEY (Supervisor_ID) REFERENCES Staff (Staff_ID)
);
				</code-block>
			
				This solution uses the discrete approach for transforming subtypes. The additive approach is also feasible (i.e., place the Person attributes into both Staff and Student, and eliminate Person entirely). We accepted either approach, but note that the discrete approach has one distinct advantage over the additive approach in this scenario. Consider what happens when someone is both a staff member and a student: we end up duplicating all the <quote>person</quote> data across both tables. This doesn<apostrophe />t occur with the discrete approach. People who didn<apostrophe />t discuss this aspect lost marks.
				
				For those who implemented the additive approach, we marked the <quote>person</quote> attributes in Staff and Student as if they were a separate Person entity.
				
				The integrated approach was definitely not suitable due to the supervision relationship between Staff and Student (which, incidentally, many people missed completely), and the mandatory attributes that exist in both Staff and Student.
				
				We also need to add an associative entity between Paper and Staff in order to resolve the many-to-many relationship:
				
				<vskip size="small" />
				
				Teach<left-brace /><underline>Staff<underscore />ID, Paper<underscore />Code</underline><right-brace />; Staff<underscore />ID FK to Staff, Paper<underscore />Code FK to Paper
				
				<code-block>
CREATE TABLE Teach
( Staff_ID NUMBER(7),
 Paper_Code CHAR(7),
 --
 CONSTRAINT Teach_PK PRIMARY KEY (Staff_ID, Paper_Code),
 CONSTRAINT Teach_FK_to_Staff FOREIGN KEY (Staff_ID) REFERENCES Staff,
 CONSTRAINT Teach_FK_to_Paper FOREIGN KEY (Paper_Code) REFERENCES Paper
);
				</code-block>
				
				It<apostrophe />s important when implementing <quote>boolean</quote> style columns such as <code>International</code> in <code>Student</code> and <code>Visible</code> in <code>Assessment</code> that you are consistent in the values that you use across all such columns (more precisely, all such columns should have the same domain). Quite a few people did something like implement one column as <code>'T', 'F'</code> and the other as <code>'True', 'False'</code>, or even more subtle, <code>'t', 'f'</code> (remembering that SQL is case sensitive). Using inconsistent domains for columns that should have the same domain could lead to subtle bugs later on.
				
				This of course is really a consequence of not having a proper <code>BOOLEAN</code> data type in SQL. However, one person did discover<emdash />possibly inadvertently, given that it isn<apostrophe />t mentioned anywhere in the documentation<emdash />that <OracleServer /> now supports the use of the <code>BOOLEAN</code> data type in <code>CREATE TABLE</code>! This certainly wasn<apostrophe />t possible in older versions, where <code>BOOLEAN</code> was available in PL/SQL only.

</answer>
			
		</section>
		
		
		<newpage />
		
		
		<section>
		
			<title>The <tt>Enrolment</tt> entity</title>

<vskip size="large" />
			
			The year of enrolment cannot be earlier than the year in which the Institute was founded. (Technically it should also not be in the future, but we cannot check this in <OracleServer />.)
				
			<answer>
			
				Enrolment(<underline>Enrolment<underscore />ID</underline>, Description, Year<underscore />Enrolled, Comments, Paper<underscore />Code, Student<underscore />ID); Paper<underscore />Code FK to Paper, Student<underscore />ID FK to Student

<code-block>
CREATE TABLE Enrolment
( Enrolment_ID NUMBER(10),
 Description VARCHAR2(100) NOT NULL,
 Year_Enrolled NUMBER(4) NOT NULL
 CONSTRAINT Enrolment_Year_Enrolled_Range CHECK (Year_Enrolled >= 1982),
 Comments VARCHAR2(4000), -- or CLOB
 Student_ID NUMBER(7) NOT NULL,
 Paper_Code CHAR(7) NOT NULL,
 --
 CONSTRAINT Enrolment_PK PRIMARY KEY (Enrolment_ID),
 CONSTRAINT Enrolment_FK_to_Student
 FOREIGN KEY (Student_ID) REFERENCES Student,
 CONSTRAINT Enrolment_FK_to_Paper
 FOREIGN KEY (Paper_Code) REFERENCES Paper
);
				</code-block>
				
				A surprising number of people appear to have missed the statement of when the Institute was founded in the first paragraph of the specification!
				
				Another very common error was to set the size of the <code>Comments</code> column to a relatively small number, like 200. Think about how much you can say in that many characters (one and a bit text messages), then consider what kinds of things you might want to enter into a general comments column. We deducted marks for anything smaller than 500 characters. When you have no idea of how much you<apostrophe />re going to get, it<apostrophe />s much better to go large than to go small!
			
			</answer>
			
		</section>

<section>
		
			<title>The <tt>Assessment</tt> entity</title>

<tabular border="1">
				<tabular-columns>
					<column align="center" left-border="|" right-border="|" />
					<column align="left" right-border="|" />
					<column align="left" right-border="|" />
				</tabular-columns>
				<tabular-body>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Assessment_ID</code></cell>
						<cell>Internally generated 10 digit identifier</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Assessment_Year</code></cell>
						<cell>4 digits</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Name</code></cell>
						<cell>Up to 50 characters</cell>
					</row>
					<row>
						<cell><tt>o</tt></cell>
						<cell><code>Description</code></cell>
						<cell>Up to 500 characters</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Type</code></cell>
						<cell>(see below)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Visible</code></cell>
						<cell>True/false, default false</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Weight</code></cell>
						<cell>0<endash />100, no decimal places</cell>
					</row>
					<row>
						<cell><tt>o</tt></cell>
						<cell><code>Maximum_Mark</code></cell>
						<cell>(see below)</cell>
					</row>
					<row-rule />
				</tabular-body>
			</tabular>

<itemised-list>
			
				<item>A new set of assessments is created for each year that a paper is offered. The year cannot be earlier than the year in which the Institute was founded. (Technically it should also not be in the future, but we cannot check this in <OracleServer />.)</item>
				
				<item>The assessment type must be one of the following: <quote>A</quote> (assignment), <quote>T</quote> (test) or <quote>X</quote> (exam).</item>
				
				<item>The <code>Maximum_Mark</code> attribute stores the maximum possible raw mark for the assessment (e.g., 30), while the <code>Weight</code> attribute stores the percentage weight of this assessment for the paper as a whole (e.g., 10<percent-sign />). If <code>Maximum_Mark</code> is not specified, then applications should use <code>Weight</code> for both.</item>
				
				<item>The <code>Visible</code> attribute controls whether or not the marks for this assessment are publicly accessible.</item>
				
			</itemised-list>
			
			<answer>
			
				Assessment(<underline>Assessment<underscore />ID</underline>, Assessment<underscore />Year, Name, Description, Type, Visible, Weight, Maximum<underscore />Mark, Paper<underscore />Code); Paper<underscore />Code FK to Paper

<code-block>
CREATE TABLE Assessment
( Assessment_ID NUMBER(10),
 Assessment_Year NUMBER(4) NOT NULL
 CONSTRAINT Assessment_Year_Range
 CHECK (Assessment_Year >= 1982),
 Name VARCHAR2(50) NOT NULL,
 Description VARCHAR2(500),
 Type CHAR(1) NOT NULL
 CONSTRAINT Assessment_Type_Valid CHECK (Type IN ('A', 'T', 'X')),
 Visible CHAR(1) DEFAULT 'F' NOT NULL
 CONSTRAINT Assessment_Visible_Valid CHECK (Visible IN ('T', 'F')),
 Weight NUMBER(3) NOT NULL
 CONSTRAINT Assessment_Weight_Range CHECK (Weight BETWEEN 0 AND 100),
 Maximum_Mark NUMBER(3),
 Paper_Code CHAR(7) NOT NULL,
 --
 CONSTRAINT Assessment_PK PRIMARY KEY (Assessment_ID),
 CONSTRAINT Assessment_FK_to_Paper
 FOREIGN KEY (Paper_Code) REFERENCES Paper
);
				</code-block>
				
			</answer>
			
		</section>
		
		
		<newpage />
		
		
		<section>
		
			<title>The <tt>Result</tt> entity</title>

<tabular border="1">
				<tabular-columns>
					<column align="center" left-border="|" right-border="|" />
					<column align="left" right-border="|" />
					<column align="left" right-border="|" />
				</tabular-columns>
				<tabular-body>
					<row-rule />
					<row>
						<cell header="yes" />
						<cell header="yes">Column</cell>
						<cell header="yes">Description</cell>
					</row>
					<row-rule />
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Assessment_ID</code></cell>
						<cell>10 digit identifier</cell>
					</row>
					<row>
						<cell><tt><hash /></tt></cell>
						<cell><code>Enrolment_ID</code></cell>
						<cell>10 digit identifier</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Raw_Mark</code></cell>
						<cell>3 digits plus 1 decimal place (i.e., 000.0)</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Weighted_Mark</code></cell>
						<cell>Floating point</cell>
					</row>
					<row>
						<cell><tt>*</tt></cell>
						<cell><code>Percentage_Mark</code></cell>
						<cell>0<endash />100, 2 decimal places</cell>
					</row>
					<row-rule />
				</tabular-body>
			</tabular>

<itemised-list>
			
				<item>The <code>Raw_Mark</code> attribute stores the raw mark awarded for an assessment. Its value should be between zero and the value of <code>Assessment.Maximum_Mark</code> (note that only the former is required for this assignment<emdash />bonus marks if you can also achieve the latter).</item>
				
				<item>The value of the <code>Weighted_Mark</code> attribute is calculated by the formula: <line-break />
				<code>Raw_Mark</code> / <code>Assessment.Maximum_Mark</code><space /> <times /><space /> <code>Assessment.Weight</code>.</item>
				
				<item>The value of the <code>Percentage_Mark</code> attribute is calculated by the formula: <line-break />
				<code>Raw_Mark</code> / <code>Assessment.Maximum_Mark</code><space /> <times /> 100.</item>
				
				<item>Note that the two calculations above are <emph>not</emph> constraints and should not be implemented as such. You may attempt to implement these calculations if you feel confident in your ability to do so, but please ensure that you complete the rest of the assignment first.</item>
				
			</itemised-list>
			
			<answer>
			
				Result(<underline>Assessment<underscore />ID, Enrolment<underscore />ID</underline>, Raw<underscore />Mark, Weighted<underscore />Mark, Percentage<underscore />Mark); Assessment<underscore />ID FK to Assessment, Enrolment<underscore />ID FK to Enrolment

<code-block>
CREATE TABLE Result
( Assessment_ID NUMBER(10),
 Enrolment_ID NUMBER(10),
 Raw_Mark NUMBER(4,1) NOT NULL,
 Weighted_Mark NUMBER NOT NULL,
 Percentage_Mark NUMBER(5,2) NOT NULL
 CONSTRAINT Result_Percentage_Mark_Range
 CHECK (Percentage_Mark BETWEEN 0 AND 100),
 --
 CONSTRAINT Result_PK PRIMARY KEY (Assessment_ID, Enrolment_ID),
 CONSTRAINT Result_FK_to_Assessment
 FOREIGN KEY (Assessment_ID) REFERENCES Assessment,
 CONSTRAINT Result_FK_to_Enrolment
 FOREIGN KEY (Enrolment_ID) REFERENCES Enrolment
);
				</code-block>
				
				A lot of people got the sizes of the various <code>NUMBER</code> columns incorrect. Remember that the number of decimal places is included in the total number of digits, not in addition to.
				
				We also accepted <code>FLOAT</code> and <code>BINARY_FLOAT</code> for <code>Weighted_Mark</code>. Anything with a fixed number of decimal places was marked down, as this is a fixed point number, not a floating point number.
				
			</answer>
			
		</section>
	
	</section>

</document>

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