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How to write Conditional Where Clause


How to write Conditional Where Clause

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descentflower
descentflower
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Hi,
I have a simple query

select name from tableInfo

i am passing two parameters to the stored procedure
@x and @y

if @x!=0 and x is not null i want to add that in where clause for exp.
select name from tableInfo where x=@x

Similarly for @y
select name from tableInfo where x=@x and y=@y

I had use dynamic query earlier but i want to avoid it.
GilaMonster
GilaMonster
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http://sqlinthewild.co.za/index.php/2009/03/19/catch-all-queries/

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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dilip_baboo
dilip_baboo
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try along these lines .....

select * from Tname
where (Tcol1 = @X OR Tcol1 is null)
AND (Tcol2 = @Y OR Tcol2 is null)


---- OR -----


select * from Tname
where Tcol1 = case when @X is null then null
when @X = 0 then null
else @X end
and
Tcol2 = case when @Y is null then null
when @Y = 0 then null
else @Y end
descentflower
descentflower
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Hi dilip,

select * from Tname
where Tcol1 = case when @X is null then null
when @X = 0 then null
else @X end
and
Tcol2 = case when @Y is null then null
when @Y = 0 then null
else @Y end

I tried this , but when i pass @x=0 it doesnt works. The Case makes it Tcol1=null.
Pandian S
Pandian S
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Hi

SELECT [NAME] FROM TABLEINFO(NOLOCK)
WHERE X = CASE WHEN @X <>0 AND @X IS NOT NULL THEN @X ELSE X END
AND Y = CASE WHEN @Y <>0 AND @Y IS NOT NULL THEN @Y ELSE Y END

Regards

descentflower
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w00t HI Thank you it worked !! w00t
GilaMonster
GilaMonster
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Just a couple things with that.

It's likely to perform badly. Take a look at the blog post I referenced earlier. Also, before you use nolock, read this: http://sqlblog.com/blogs/andrew_kelly/archive/2009/04/10/how-dirty-are-your-reads.aspx

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass


descentflower
descentflower
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GilaMonster (6/17/2009)
Just a couple things with that.

It's likely to perform badly. Take a look at the blog post I referenced earlier. Also, before you use nolock, read this: http://sqlblog.com/blogs/andrew_kelly/archive/2009/04/10/how-dirty-are-your-reads.aspx


Hi Gila,
As i am a newbie i donno so,
What bad effect will the query with 'case in where clause' bring ?
GilaMonster
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Poor performance. Generally that kind of query does not use indexes effectively and often does table scans. On small tables that aren't used too often that won't be a major issue. On larger tables or busy systems it is.

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass


Pyay Nyein
Pyay Nyein
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Hi,

Half of the code is already in your question..change the and/or in the where clause according to ur requirement

SELECT [name]
FROM tableInfo
WHERE (@x <> 0 and @x is not null and x = @x)
and/or (@y <> 0 and @y is not null and y = @y)
Go


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