REFERENCE a table with a FOREIGN KEY
In your database, you want the professors table to reference the universities table. You can do that by specifying a column in professors table that references a column in the universities table.
As just shown in the video, the syntax for that looks like this:
ALTER TABLE a
ADD CONSTRAINT a_fkey FOREIGN KEY (b_id) REFERENCES b (id);
Table a should now refer to table b, via b_id, which points to id. a_fkey is, as usual, a constraint name you can choose on your own.
Pay attention to the naming convention employed here: Usually, a foreign key referencing another primary key with name id is named x_id, where x is the name of the referencing table in the singular form.
Deze oefening maakt deel uit van de cursus
Introduction to Relational Databases in SQL
Praktische interactieve oefening
Probeer deze oefening eens door deze voorbeeldcode in te vullen.
-- Rename the university_shortname column
ALTER TABLE ___
___ ___ university_shortname ___ ___;