When we don't need a primary key for our table?

Question

Will it ever happen that we design a table that doesn\'t need a primary key?

Answer 1

No.

The primary key does a lot of stuff behind-the-scenes, even if your application never uses it.

For example: clustering improves efficiency (because heap tables are a mess).

Not to mention, if ANYONE ever has to do something on your table that requires pulling a specific row and you don't have a primary key, you are the bad guy.