Why should I use primary ID's for associated tables

Question

I've been reading through questions explaining why primary ID's should always be used in tables, especially if a record in one table needs to associate with a record in another table. However in my case the table is one of users, so has a name field. Surely for associating I could just use the name of the users to associate with, or am I missing something.

Answer 1

One of the main reasons why you should have a Primary ID is because it should be permanent value since it could be used for referencing foreign keys from the other tables.

You can use name provided that:

• There is a key defined on it. (obviously, a Primary Key or a Unique Key)
• It cannot be modified. You have stated in your question: "..associating I could just use the name of the users to associate with..". What if you want to modify the name and there are already records that are depending on it?