Eine Einführung in


CREATE TABLE with a composite primary key


A composite key has more than one attribute (field). In this example we store details of tracks on albums - we need to use three columns to get a unique key - each album may have more than one disk - each disk will have tracks numbered 1, 2, 3...

The primary key must be different for each row of the table. The primary key may not contain a null.

Execute tidy up code silently

Specific to MySQL
We must explicitly state that the components are NOT NULL.