G51DBS 2008-2009 Coursework 2

Worth 5% of the total mark.
Deadline: I would prefer to mark it in the lab on the 18th (please also submit your coursework to cw, id 183, even if you had it marked in the lab - for the record). You can submit to cw without any points deducted until Friday the 20th of February, 23:59. After that you can still submit until the 27th of February at 16:00 but I will subtract points for lateness.

General instructions

Make sure you have an Oracle account

Please make sure you can use Oracle first. Instructions are in Getting started with Oracle.

Run SQL from a file

It is possible to create the same database and insert the tuples interactively, and you are welcome to practice this way, but for the exercise please place all your SQL statements in a file. Call it cw2.sql, save it in the directory from which you start sqlplus, and run the statements by typing start cw2.sql; at the sqlplus prompt.
We will ask to see your file in the lab when we are marking the exercise. Please also submit it to cw, coursework id is 183.
The comment character in SQL is --. For example files, look at the last year's exercise solutions here .

Exercise

Create a file containing SQL statements which will create tables described below and populate them with specified tuples. Run statements from the file to create a database instance.

Tables:

Participant with attributes pnumber and name. Values for pnumber are of type INT and values for name are of type string of at most 50 characters (VARCHAR(50)). Neither can be NULL. The primary key is pnumber. There are no foreign keys.
Competition with attributes cdate and place. Values in cdate are of type DATE, values in place are strings of at most 20 characters. Both together are the primary key. There are no foreign keys.
Result with attributes pnumber (foreign key into Participant), cdate, place (foreign key into Competition) and points which is of type INT. The primary key is pnumber, cdate and place together.

Tuples:

Insert data about:

participants Alice with pnumber 113, Bob with pnumber 115, and Chris with pnumber 120.
competitions in Nottingham on the 16th of February 2009, Birmingham on the same date, and London on the 17th of February 2009. You can input dates as strings in DD-MON-YY format, for example '16-Feb-09'.
results for Alice in Nottingham on the 16th of 20 points and for Bob in Nottingham on the 16th of 30 points.

How to fix mistakes

If you make a mistake and want to remove a table called Sometable (together with all its contents), type DROP TABLE Sometable; at the sqlplus prompt.

If you want to remove or change a tuple, use DELETE FROM Sometable WHERE ... or UPDATE Sometable SET ... WHERE ...

How to check the result

To see the result, type SELECT table_name FROM user_tables;
This will give you a list of all the tables you have made. If you want to see the details for a table called Sometable, type

DESCRIBE Sometable;
This will list the column names, data types, and whether NULLs are allowed for Sometable.

If you want to see which tuples are in Sometable, type

SELECT * FROM Sometable;
This will list all the rows in Sometable.

We will use these commands to mark the exercise. Here is the model output

Marking scheme

You get full marks (5/5) if your output for DESCRIBE is as in the model output, rows in the tables are similar to the model output, and keys are declared properly. To check whether you defined primary keys correctly try, for example, adding a new participant with the same number as some participant already in the database, and a different name (should not succeed). To check whether you defined foreign keys properly, try to remove Nottingham competition on the 16th drop the whole table Competition - this should be impossible since competitions are referenced by the Result table.
Mistakes such as not declaring constraints properly will be penalised by 1 or 2 marks.