Question

I need to create a stored procedure which takes 12 arguments and the query is filtered with a different combination of this arguments. All 12 arguments are not mandatory as if I pass 3 or 5 or 12 arguments depends on search inputs entered by user.

I can create 2 ways, either using a dynamic SQL query or using ‘Case where’ statements. Example of these queries are as below:

1. Dynamic Query

   DECLARE @sql VARCHAR(MAX) 
   DECLARE @condition VARCHAR(MAX)=''
   Declare @var1 varchar(10)
   Declare @var2 varchar(10)
   Declare @var3 varchar(10) 
   SET  @sql='SELECT * FROM TableDemo1 TD1 WITH(NOLOCK)
    INNER JOIN TableDemo2 TD2 ON TD1.Column1=TD2.Column2'
   if(@var1 <>0 and @var1 is not null)
   begin
       if(@condition<>'')
       begin
           set @condition=@condition + ' and TD1.columnTest1='+@var1)
       end
       else
       begin
           set @condition=' where TD1.columnTest1='+@var1
       end
   end
   if(@var2 <>0 and @var2 is not null)
   begin
       if(@condition<>'')
       begin
           set @condition=@condition + ' and TD2.columnTest2='+@var2)
       end
       else
       begin
           set @condition=' where TD2.columnTest2='+@var2
       end
   end
   
   if(@var3 <>0 and @var3 is not null)
   begin
       if(@condition<>'')
       begin
           set @condition=@condition + ' and TD1.columnTest3='+@var3)
       end
       else
       begin
           set @condition=' where TD1.columnTest3='+@var3
       end
   end
   SET @sql=@sql+@condition
   EXEC(@sql)
   

2. Query with CASE WHERE

   Declare @var1 varchar(10)
   Declare @var2 varchar(10)
   Declare @var3 varchar(10)
   SELECT *
   FROM TableDemo1 TD1 WITH(NOLOCK)
       INNER JOIN TableDemo2 TD2 ON TD1.Column1=TD2.Column2
   WHERE
     (CASE WHEN   
       (@var1<>0 and @var1 is not null)   
       THEN  
       CASE WHEN TD1.columnTest1=@var1 THEN 1 ELSE 0 END  
       ELSE 1 END)=1  
     AND   
     (CASE WHEN  
       (@var2<>0 and @var2 is not null)   
       THEN  
       CASE WHEN TD2.columnTest2=@var2 THEN 1 ELSE 0 END  
       ELSE 1 END)=1  
     AND
     (CASE WHEN
       (@var3<>0 AND @var3 IS NOT NULL)
       THEN
       CASE WHEN TD1.columnTest3 = @var3
       THEN 1 ELSE 0 END
       ELSE 1 END) =1
   

This is just part of my stored procedure, there are 7-8 tables with joins and as above in query variety in conditions.

If I use a dynamic query, SQL Server will have to create an execution plan every time, but if I use ‘case where’ it also makes the query slow.

I am aware of disadvantages of dynamic SQL, but which technique I should use?

Answer 1

Generally it depends, but most often I use dynamic queries as a last resort. Regarding your question, I would most probably go with the CASE solution, but I think your CASE expressions are unnecessarily complicated. I would replace the WHERE clause with something like this:

...
WHERE
    TD1.columnTest1 = COALESCE(NULLIF(@var1, 0), TD1.columnTest1)
    AND   
    TD2.columnTest2 = COALESCE(NULLIF(@var2, 0), TD2.columnTest2)
    AND   
    TD1.columnTest3 = COALESCE(NULLIF(@var3, 0), TD1.columnTest3)

With proper indexing this shouldn’t be too slow.