I've been wondering about this for some time. I like avoid joins when possible by using queries like this:

select a.field, b.field from a,b where a.something = b.something

Does this have the same performance etc. as the equivalent join?

asked Oct 11 '11 at 14:04

willirl's gravatar image


One Answer:

Yes, it actually is a join. I am not aware of any database that does not handle it the same way.

The explicit join syntax has, however, some advantages from the readability and maintainability perspective:

  • No accidental cross join possible
  • Grouped join predicates (all join conditions at one place in the statement)
  • Distinction between join predicates and other predicates
  • Easy outer join and even full outer join

answered Oct 11 '11 at 14:58

Markus%20Winand's gravatar image

Markus Winand ♦♦