Lookup tables - should I use an id column or just use the value?

Question

I have many lookup tables that look like:

id(pk) type(unique)
---
1 UNIVERSITY OF ARIZONA
2 UNIVERSITY OF MIAMI
3 TOKYO UNIVERSITY

Let's say type is a unique string in all cases.

I am questioning whether I should use the id(pk) or just do:

type(pk)
----
UNIVERSITY OF ARIZONA
...

Answer 1

You should use the primary key. Here are some reasons:

• Integers are generally more efficient than strings for joins.
• Integers are definitely more efficient from a storage perspective -- the strings are longer than the numbers.
• You might want to change the name one day, say, 'UNIVERSITY OF ARIZONA (TUCSON)'.
• Primary keys are really what is expected for the foreign key relationship.