Should I COUNT(*) or not?

Question

I know it\'s generally a bad idea to do queries like this:

SELECT * FROM `group_relations`

But when I just want the count, should I go for this

Answer 1

It should depend on what you are actually trying to achieve as Sebastian has already said, i.e. make your intentions clear! If you are just counting the rows then go for the COUNT(*), or counting a single column go for the COUNT(column).

It might be worth checking out your DB vendor too. Back when I used to use Informix it had an optimisation for COUNT(*) which had a query plan execution cost of 1 compared to counting single or mutliple columns which would result in a higher figure