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.
Bu egzersiz
Introduction to Relational Databases in SQL
kursunun bir parçasıdırUygulamalı interaktif egzersiz
Bu örnek kodu tamamlayarak bu egzersizi bitirin.
-- Rename the university_shortname column
ALTER TABLE ___
___ ___ university_shortname ___ ___;