> > Can anybody give me somes notes on uses of "IN" and "EXIST". How are
> > they being use? Which is much preferred?
> >
> > Thanks
>
> to quote Celko
> "An EXISTS predicate can use indexes to find.. or fail, whereas the IN
> predicate ofen has to build the results of the subquery in a working

table"

>
> not sure exactly how FB is optimised in this regard

Celko is talking rubbish here. "can use indexes" -> this is implementation
defined. How an engine handles whatever statement has nothing to do
with the logical operator "EXISTS" or "IN".

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL
Server.
Upscene Productions
http://www.upscene.com