Ravinder,
> Both the following query will throw same result (assuming empname aslo exist
> in Dept)
The issue is whether or not the referenced select column exists in the
sub-select table. If it does *not*, you get the behavior you've seen.
> Or Could u pls tell me exactly how the Optimizer transform the above
> query(ies)
No offense, but could you stick to standard English spellings? I find
"online jargon" like "u pls" doesn't scan well and makes it more work for me
to read e-mails. Thanks!
--
-Josh Berkus
Aglio Database Solutions
San Francisco