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how to return dynamic column name in stored procedure?

Posted on 2013-01-07
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Last Modified: 2013-01-09
in my stored procedure, i group the result set to return multiple groups like 'Sheet1', 'Sheet2'

Here is my the grouping return in my SP:
select [Sheet + @loop] = 'Sheet' + Convert(varchar(10), @loop), * from @Result result
WHERE result.State = (Select top 1 State from @Group where RowID = @loop) AND
      
      SELECT @loop = @loop + 1
END

How can i make the first column name as 'Sheet1', 'Sheet2', 'Sheet3', etc.
I know my syntax is wrong as [Sheet + @loop], but just want to give u some idea
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Question by:hongclub
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7 Comments
 
LVL 19

Expert Comment

by:Rimvis
ID: 38754592
Hi hongclub,

You will have to use dynamic SQL for that. Please see example bellow. If parameters for you query are coming from external sources, make sure you are validating it against SQL injection attacks.

DECLARE @sSQL NVARCHAR(MAX)
SET @sSQL = N'select [Sheet' + Convert(varchar(10), @loop) +'] = ''Sheet' + Convert(varchar(10), @loop)+ ', * from ' + @Result + ' result '
			+ N'WHERE result.State = (Select top 1 State from ' + @Group + ' where RowID = ' + Convert(varchar(10), @loop)+ ') AND ...'
			
EXEC (@sSQL)
         

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Author Comment

by:hongclub
ID: 38755534
thanks, i tired it, however there are two issues i am facing

(1) it returned me error, it said 'Must declare the scalar variable "@Result", but i have that @Result table declare also, so i twist my code to this
WHILE (@loop < = (Select count(*) from @Group))
-- WHILE (@loop < = 2)
BEGIN
DECLARE @sSQL NVARCHAR(MAX)
SET @sSQL = N'select [Sheet' + Convert(varchar(10), @loop) +'] = ''Sheet' + Convert(varchar(10), @loop)+ ', * from @Result result '
                  + N'WHERE result.State = (Select top 1 State from @Group ' + ' where RowID = ' + Convert(varchar(10), @loop)+ ') AND '

                  
EXEC (@sSQL)
END


(2) after i change, the sp is so slow, it took 10 seconds to run, and eventually i stop executing the SP, is it because it is in the while loop
0
 

Author Comment

by:hongclub
ID: 38755963
any suggestion, can't believe it is so complicated to generate a dynamic column name
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LVL 19

Accepted Solution

by:
Rimvis earned 2000 total points
ID: 38758006
So @Result is a table variable? You have to change it to temporary table to use it in dynamic SQL. Besides that, temp tables generally are performing better with large (>1000 records) datasets.

Also, I don't see @loop incremented anywhere. Could it be you are running an infinite loop?
0
 

Author Comment

by:hongclub
ID: 38759864
thanks Rimvis, i got it working using #Result dynamic table
0
 

Author Comment

by:hongclub
ID: 38759869
another question, can i create dynamic table with dynamic column
0
 
LVL 19

Expert Comment

by:Rimvis
ID: 38761250
What do you mean? Could you give an example please?
0

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