What's the best practice for primary keys in tables?

Question

When designing tables, I\'ve developed a habit of having one column that is unique and that I make the primary key. This is achieved in three ways depending on requirements

Answer 1

All tables should have a primary key. Otherwise, what you have is a HEAP - this, in some situations, might be what you want (heavy insert load when the data is then replicated via a service broker to another database or table for instance).

For lookup tables with a low volume of rows, you can use a 3 CHAR code as the primary key as this takes less room than an INT, but the performance difference is negligible. Other than that, I would always use an INT unless you have a reference table that perhaps has a composite primary key made up from foreign keys from associated tables.