Why use an auto-incrementing primary key when other unique fields exist?

Question

I\'m taking a course called \"database systems\" and for our class project I have to design a website.

Here\'s an example of a table I created:

CREATE TA         


        

Answer 1

For instance, integer search (?id=5) is much way faster and has higher cardinality than string search (?username=bob). Another example, uid is auto_increment, so you don't have to insert it explicitly but it will auto increment in each insert query.

PS: Your prof is soooo wrong about it :D