What is the difference between in and exists.
Ex: select * from emp where empno in(....) and
select * from emp where empno exists(....)
What is the difference between a Join and Union and Union
and UnionAll.
Answer Posted / manoj pandey
Check below links to know the reason with examples from my blog posts:
IN vs EXISTS vs JOIN: http://sqlwithmanoj.wordpress.com/2011/02/15/not-in-not-exists-joins-with-null-values/
UNION vs UNION ALL: http://sqlwithmanoj.wordpress.com/2010/12/30/why-union-all-is-faster-than-union/
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