SQL Injection in Stored Procedure & Preventing from the same

Following is the small example of creating a stored procedure. ==================================================================== CREATE PROC sp_login (@loginid nvarchar(25),@password nvarchar(25)) AS DECLARE @SQLString VARCHAR(500) DECLARE @loginid VARCHAR(64) DECLARE @password VARCHAR(64) /* Build the SQL string once.*/ SET @SQLString = ‘SELECT * from cust_users WHERE login_id = ‘+ ””+@loginid+”” + ‘AND password = ‘+ ””+@password+”” EXECUTE sp_executesql @SQLString