Concatenate Parameters in stored procedure

Question

I want to concatenate parameter value with string in a stored procedure. Because I want to complete select query: where condition. For that '@size_from' parameter must be concatenate with string, which contains select query.

My stored procedure:

dbo.GetDiamondDetail

 ALTER PROCEDURE [dbo].[GetDiamondDetail]
        @size_from numeric(18,2),
        @size_to numeric(18,2),
        @price_from int,
        @price_to int,
        @price_car_from int,
        @price_car_to int,
        @clarity_from nvarchar(6),
        @clarity_to nvarchar(6),
        @cut_from varchar(50),
        @cut_to varchar(50),
        @color_from varchar(50),
        @color_to varchar(50),
        @certi_lbl varchar(100),
        @depth_from numeric(18,2),
        @depth_to numeric(18,2),
        @table_from numeric(18,2),
        @table_to numeric(18,2),
        @polish_from varchar(50),
        @polish_to varchar(50)


AS
BEGIN
      SET NOCOUNT ON;     

      Declare @Test Varchar(MAX)

        Set @Test=' SELECT  
            dd.stock_no,
          d.diamond_shape,
          d.diamond_img,
          dd.size,
          c.cut_nm,
          co.color_nm,
          clr.clarity_nm,
          dd.off_rap,
          dd.price,
          dd.price_per_carat,
          (dd.price * 2) AS [total_price],
          f.fluo_nm,
          dd.depth,
          dd.diamond_table,
          dd.measurement,
          cert.cert_nm,
          p.polish_type,
          s.symmetry_type,
          dlr.dealer_email

       FROM diamond_detail dd
         JOIN diamond d ON dd.diamond_id=d.diamond_id
         JOIN cut c ON dd.cut_id=c.cut_id
         JOIN color co ON dd.color_id=co.color_id
         JOIN clarity clr ON dd.clarity_id=clr.clarity_id
         JOIN fluorescence f ON dd.fluo_id=f.fluo_id
         JOIN certificate cert ON dd.cert_id=cert.cert_id
         JOIN polish p ON dd.polish_id=p.polish_id
         JOIN symmetry s ON dd.symmetry_id=s.symmetry_id
         JOIN dealer dlr ON dd.dealer_id=dlr.dealer_id 
         JOIN width w ON dd.width_id=w.width_id
    where '


        set @Test=@Test+'dd.size_from>='+@size_from


         PRINT @Test
         EXEC (@Test) 
END

Answer 1

Why make it so complicated and use strings? Just execute the statement:

 ALTER PROCEDURE [dbo].[GetDiamondDetail]
        @size_from numeric(18,2),
        @size_to numeric(18,2),
        @price_from int,
        @price_to int,
        @price_car_from int,
        @price_car_to int,
        @clarity_from nvarchar(6),
        @clarity_to nvarchar(6),
        @cut_from varchar(50),
        @cut_to varchar(50),
        @color_from varchar(50),
        @color_to varchar(50),
        @certi_lbl varchar(100),
        @depth_from numeric(18,2),
        @depth_to numeric(18,2),
        @table_from numeric(18,2),
        @table_to numeric(18,2),
        @polish_from varchar(50),
        @polish_to varchar(50)


AS
BEGIN
      SET NOCOUNT ON;     

      SELECT  
          dd.stock_no,
          d.diamond_shape,
          d.diamond_img,
          dd.size,
          c.cut_nm,
          co.color_nm,
          clr.clarity_nm,
          dd.off_rap,
          dd.price,
          dd.price_per_carat,
          (dd.price * 2) AS [total_price],
          f.fluo_nm,
          dd.depth,
          dd.diamond_table,
          dd.measurement,
          cert.cert_nm,
          p.polish_type,
          s.symmetry_type,
          dlr.dealer_email

       FROM diamond_detail dd
         JOIN diamond d ON dd.diamond_id=d.diamond_id
         JOIN cut c ON dd.cut_id=c.cut_id
         JOIN color co ON dd.color_id=co.color_id
         JOIN clarity clr ON dd.clarity_id=clr.clarity_id
         JOIN fluorescence f ON dd.fluo_id=f.fluo_id
         JOIN certificate cert ON dd.cert_id=cert.cert_id
         JOIN polish p ON dd.polish_id=p.polish_id
         JOIN symmetry s ON dd.symmetry_id=s.symmetry_id
         JOIN dealer dlr ON dd.dealer_id=dlr.dealer_id 
         JOIN width w ON dd.width_id=w.width_id
    where dd.size_from >= @size_from;

END

Answer 2

change your code for where condition to handle null value, other wise while concatenation every thing goes to null and does not give the result.

First of all you must declare your temp variable as NVARCHAR data type to accept unicode value.

    --1. do not give where in first string, but check it.

    if(isnull(@size_from,'')  != ''
    set @Test=@Test+' where dd.size_from>='+@size_from


         PRINT @Test
         EXEC (@Test) 
END