PLS HELP TO AVOID SELECT & USE CASE SIMILAR TO IF

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PLS HELP TO AVOID SELECT & USE CASE SIMILAR TO IF

Author

Topic

Abhilash
Starting Member

1 Post

Posted - 2009-08-30 : 08:22:17

Hello, I am new to SQLServer Programming and would like some help from you who are veterans to programming.....

I would like to know how to use CASE similar to using IFs...

I know that the common usage of CASE is like this...

DECLARE @TestVal int
SET @TestVal = 3

SELECT
CASE @TestVal
WHEN 1 THEN 'First'
WHEN 2 THEN 'Second'
WHEN 3 THEN 'Third'
ELSE 'Other'
END

But I want to use the Case similar to the usage of Switch Case statement in C....

i.e.,

Declare @Determiner int
Set @Determiner = <some value>

If @Determiner = 1
Begin
Update tbl1....
Update tbl2....
End

Else If @Deteminer = 2
Begin
Update tbl1....
Update tbl2....
Update tbl3....
End

,etc...

Using Select Case returns some value right?I dont want that to happen...

How to avoid using Select so that i can use Case similar to if..else.. construct? Pls Help

Hopefully expecting your reply at the earliest

Thanking You

Abhilash

TG
Master Smack Fu Yak Hacker

6065 Posts

Posted - 2009-08-30 : 12:17:41

You're right that a CASE is an expession that returns a value based on conditions. Where as an IF/ELSE IF/Else block is used as a Control of Flow technique. They are both valid sql that are simply two different t-sql tools.

You can do something like this:


update <tblAlias> set
   <tblAlias>.col1 = case when @Determiner = 1 then ... 
                          when @determiner = 2 then ...
                          else ... 
                          end
from  ...

Be One with the Optimizer
TG

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