IF Exist vs Count

Posted Date: 03 Jul 2008 Resource Type: Code Snippets Category: SQL

Posted By: M. Irfan Member Level: Gold
Rating:

Points: 4

IF EXIST Vs COUNT(*)

Many times we see that people use count(*) to get the condition that if we have any record like

IF (SELECT COUNT(*) FROM Employee where Salaried =0 ) >0

BEGIN

PRINT 'Yes Got It'

-- Do your calculation here.

END

We are doing some calculation if we get Salaried=0 for at least once. And I know many times we use the same trick.

"The cost for getting the count(*) is that it counts all the data we get by where clause."

Use if exist to reduce this overhead.

IF EXISTS(SELECT * FROM Employee where Salaried =0)

BEGIN
PRINT 'Yes Get it'

-- Do your calculation here.

END

In this as soon as we get the first record further execution stops and it comes out of the if condition with true. If this not get any result then will cost same as above query.

For more details, visit http://matespoint.blogspot.com/2008/03/if-exist-vs-count-sql-server.html

Responses

Author: Satish N Raykar 04 Jul 2008

Member Level: Bronze Points : 1

Thank you providing good information, i will use the same hence forth...

Author: Satyanarayan SushilKumar Bajoria 04 Jul 2008

Member Level: Gold Points : 1

Hi,

Thanks for your valuable tips on If Exist and Count(*).

Keep posting such valuable tips.

Thanks for sharing your knowledge.

Thanks and Regards
S.S.Bajoria

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