Should I design a table with a primary key of varchar or int?

Question

I know this is subjective, but I\'d like to know peoples opinions and hopefully some best practices that I can apply when designing sql server table structures.

I pe

Answer 1

I would definitely recommend using an INT NOT NULL IDENTITY(1,1) field in each table as the primary key.

With an IDENTITY field, you can let the database handle all the details of making sure it's really unique and all, and the INT datatype is just 4 bytes, and fixed, so it's easier and more suited to be used for the primary (and clustering) key in your table.

And you're right - INT is an INT is an INT - it will not change its size of anything, so you won't have to ever go recreate and/or update your foreign key relations.

Using a VARCHAR(10) or (20) just uses up too much space - 10 or 20 bytes instead of 4, and what a lot of folks don't know - the clustering key value will be repeated on every single index entry on every single non-clustered index on the table, so potentially, you're wasting a lot of space (not just on disk - that's cheap - but also in SQL Server's main memory). Also, since it's variable (might be 4, might be 20 chars) it's harder to SQL server to properly maintain a good index structure.

Marc