Confused. Need some help about SQL coding

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Confused. Need some help about SQL coding

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azimuth73
Starting Member

3 Posts

Posted - 2007-06-14 : 11:32:14

hi im a little bit confused. are the two pieces of code similar? what are the differences. i really need to know that coz i wont get access to a SQL machine until monday.


select	lastname
from	emp
where	sex = 'F' and
	salary>(		select	avg(salary)
			from	emp
			group by sex
			having	sex='M'	)


select	lastname
from	emp
where	sex = 'F' and
	salary>(	select	avg(salary)
			from	emp
			where	sex='M'	)

also is it wise to use Group by and having in sub-queries?

harsh_athalye
Master Smack Fu Yak Hacker

5581 Posts

Posted - 2007-06-14 : 11:38:57

Although both queries produces same result, GROUP BY and HAVING is unnecessary where you can simply put same condition in WHERE clause.

Harsh Athalye
India.
"The IMPOSSIBLE is often UNTRIED"

Kristen
Test

22859 Posts

Posted - 2007-06-14 : 11:41:01

I think I read that SQL Query Plan Optimizer will automatically move HAVING to WHERE clause where appropriate.

Kristen

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