Re:Writing more legible SQL
by sundvor on Friday November 04, 2016 @04:47AM
(#12871141)
Great, thanks for that - I've been using (typically INNER) JOIN .. ON .. for all my life, well 20 odd years of development, and not once did I ever put the ON clause into WHERE. :)
I can vaguely recall seeing it a few times now, actually, and being rather confused as to why you'd do it that way - as perhaps it was a more optimal way of putting it, and that I'd done it wrong all the time?
As you state though, it's just bad; WHERE clauses ought to be used for filtering the data, not declaring how the tables join. Glad to have cleared that up. :)
Re:Writing more legible SQL
by T-hawk on Friday November 04, 2016 @07:11PM
(#12876998)
You'd do it that way if you just didn't know any better. "Two tables where A = B" falls into a natural line of thinking for someone who picked up SQL ad hoc rather than formally learning what a join is and the syntax for it.
I can vaguely recall seeing it a few times now, actually, and being rather confused as to why you'd do it that way - as perhaps it was a more optimal way of putting it, and that I'd done it wrong all the time?
As you state though, it's just bad; WHERE clauses ought to be used for filtering the data, not declaring how the tables join. Glad to have cleared that up. :)