sql query not printing

Question

I am trying to run a dynamic query but for some odd reason its not running. Its not even printing. Please can anyone tell me why is the below dynamic query not printing.

DECLARE @CLIENTPK_NEW AS VARCHAR(50)
DECLARE @CGNEEPK AS VARCHAR(50)
DECLARE @TYPE AS VARCHAR(10)

SET @CLIENTPK_NEW='6EF77AAA-1A7B-4D03-A448-D1088DED4134'
SET @CGNEEPK= NULL
SET @TYPE='Mag'

DECLARE @SQL NVARCHAR(MAX)       

SET @SQL = '    
SELECT       
PUBLISHER
FROM CLIENT_SHIPPINGREPORTDATA_FUNCTION('
  + @CLIENTPK_NEW + ' , ' 
  + @CGNEEPK + ' , ' 
  + @TYPE +' )' <=== This is the troubled line, but not sure what is error is.

PRINT  @SQL    <== **Why is this not priniting**

Many thanks

Answer 1

You are adding string values to a null value (@CGNEEPK) which results in NULL. When you print NULL, you see nothing. You need to use ISNULL(@CGNEEPK, '') instead.