Disallow NULL values with SET NOT NULL
The professors table is almost ready now. However, it still allows for NULLs to be entered. Although some information might be missing about some professors, there's certainly columns that always need to be specified.
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.
-- Disallow NULL values in firstname
___ ___ professors
ALTER COLUMN ___ SET NOT NULL;