IF i = NULL THEN SELECT 'Result is True' ELSEIF NOT(i = NULL) THEN SELECT 'Result is False' ELSE SELECT 'Result is Unknown'; The IF statement performs actions only for those comparisons that evaluate to True.
IF i = NULL THEN SELECT 'Result is True' ELSEIF NOT(i = NULL) THEN SELECT 'Result is False' ELSE SELECT 'Result is Unknown'; 該IF語句僅對那些評估為 True 的比較執行操作。