SQLZOO, CREATE TABLE with a foreign key

Ingres
A foreign key references is where one field "links" to another table. The database will maintain referential integrity - this means that there must be a corresponding record in the other table - in this example each track must be on an album that exists in the album table. The field (or fields) linked to must be unique - usually the other field is the primary key of the other table. 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...	Run the tidy code silently CREATE TABLE album( id CHAR(10) NOT NULL PRIMARY KEY, title VARCHAR(100), artist VARCHAR(100) ); CREATE TABLE track( album CHAR(10), dsk INTEGER, posn INTEGER, song VARCHAR(255), FOREIGN KEY (album) REFERENCES album(id) );
Specific to Ingres
none

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