When I am reviewing code of a stored procedure I find some interesting facts. The developer sends the date parameter as a string and then converts the date columns of the table to string to compare value. Like this WHEN CONVERT(VARCHAR, examdate, 105) = CONVERT(VARCHAR, @P_Examdt, 105); @P_Examdt – The parameters of stored procedure 1. I don't understand why ? 2. Is it decreasing the performance of the query ? If anyone have any comments please suggest.