Listing 7: Code That Incorrectly Resets @@ERROR to 0
/* Update fails with a trappable error. */
     
UPDATE table1
SET  col1 = 'x'
WHERE …..                                   -- @@ERROR = non-zero
     
IF @@ERROR <> 0                      -- @@ERROR = non-zero
BEGIN                                            -- @@ERROR = 0
   SET @err_status = @@ERROR  -- Capture the @@ERROR value.
   ROLLBACK                                   -- Rollback correctly done 
   RETURN @err_status                  -- Returns 0 (i.e., SUCCESS)
END