Dynamic sql in functions

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Dynamic sql in functions

abhilash.kalwa

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Points: 62
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November 2, 2010 at 4:01 am

#388145

Below is the dynamic statement which i try to excecute and throws error.
Can any one suggest me the alternate way to return the value.
CREATE FUNCTION dbo.fnDatafilter(@P_DTMOId AS BIGINT ,
@P_AccessibleDataFilters AS Varchar(4000) ,
@P_ActivityType AS varchar(100) ,
@DFTableName AS varchar(100) ,
@DFColumnName AS varchar(100)
)
RETURNS CHAR ( 1 )
AS
BEGIN
DECLARE @V_INCLUDE CHAR(1)
SET @V_INCLUDE = '0'
DECLARE @v_SQLSTRING nvarchar(max)
SET @v_SQLSTRING = ''
SET @v_SQLSTRING='IF NOT EXISTS ( SELECT ''1'' FROM '+ @DFTableName +'DataFilter WHERE '+@DFColumnName +'= @P_DTMOId AND ActivityType = @P_ActivityType AND Status = ''A'') '
SET @v_SQLSTRING = @v_SQLSTRING + 'BEGIN '
SET @v_SQLSTRING = @v_SQLSTRING + ' SELECT @V_INCLUDE = ''1'''
SET @v_SQLSTRING = @v_SQLSTRING + ' END'
SET @v_SQLSTRING = @v_SQLSTRING + ' ELSE'
SET @v_SQLSTRING = @v_SQLSTRING + ' BEGIN'
SET @v_SQLSTRING = @v_SQLSTRING + ' IF EXISTS ( SELECT ''1'' FROM '+ @DFTableName +'DataFilter WHERE '+@DFColumnName +' = @P_DTMOId AND ActivityType = @P_ActivityType AND Status = ''A'' '
SET @v_SQLSTRING = @v_SQLSTRING + ' AND DataFilterDefinitionOID IN ( SELECT OID FROM fGetBigIntList_221000 ( @P_AccessibleDataFilters ))) '
SET @v_SQLSTRING = @v_SQLSTRING + ' BEGIN'
SET @v_SQLSTRING = @v_SQLSTRING + ' SELECT @V_INCLUDE = ''1'' '
SET @v_SQLSTRING = @v_SQLSTRING + ' END '
SET @v_SQLSTRING = @v_SQLSTRING + 'END '
--print @v_SQLSTRING
EXEC @v_SQLSTRING
RETURN ( @V_INCLUDE )
END
The output of this function is used in where condition of another procedure.

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spaghettidba SSC Guru Points: 105732 More actions · Answer 1

I'm afraid this can't be done. UDF cannot execute dynamic SQL.

Some possible alternatives:

a) Code it as a stored procedure

b) Use IF statements to code a distinct SQL for each table (ugly)

c) Code it as CLR function

As a side note, scalar UDFs perform really bad. Consider using ITVFs instead.

Hope this helps

Gianluca

-- Gianluca Sartori

ChrisM@Work SSC Guru Points: 186127 More actions · Answer 2

In addition to the key points raised by Gianluca, consider also the performance implications of putting this into a WHERE clause.

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden

Pulivarthi Sasidhar SSCertifiable Points: 6706 More actions · Answer 3

Pulivarthi Sasidhar

SSCertifiable

Points: 6706

November 2, 2010 at 5:05 am

#1245276

Can you please post the error.....