Drop "firstname" and "lastname"
The firstname and lastname columns of affiliations were used to establish a link to the professors table in the last exercise – so the appropriate professor IDs could be copied over. This only worked because there is exactly one corresponding professor for each row in affiliations. In other words: {firstname, lastname} is a candidate key of professors – a unique combination of columns.
It isn't one in affiliations though, because, as said in the video, professors can have more than one affiliation.
Because professors are referenced by professor_id now, the firstname and lastname columns are no longer needed, so it's time to drop them. After all, one of the goals of a database is to reduce redundancy where possible.
This exercise is part of the course
Introduction to Relational Databases in SQL
Exercise instructions
Drop the firstname and lastname columns from the affiliations table.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
-- Drop the firstname column
___ ___ affiliations
DROP ___ firstname;
-- Drop the lastname column
___
___;