CSN <cool_screen_name90001@yahoo.com> writes:
> Just wondering - does PG support derived tables? I'm
> not really sure what the difference is between them
> and subqueries.
None whatever, at least using the definition offered by your second
reference:
A derived table is a select statement inside parenthesis, with
an alias, used as a table in a join.
The SQL92 spec appears to use the phrase in exactly this way (except
they don't require the construct to appear in a join, as indeed we don't
either; the most correct explanation would probably be "used as a table
in a FROM clause").
MySQL often has their own spin on such terms ;-). I'm not sure what
MySQL 4.1 actually supports in this line. But I'll make a side bet that
they don't yet optimize them as well as we do ...
regards, tom lane
