SQL查詢與另一

Question

下面的代碼產生一個錯誤替換表的記錄：

select lastname, firstname, workphone, homephone 
from members if (workphone is null) then workphone = homephone; 

我想從一個名爲members表中選擇lastnames，firstnames和你的電話號碼。如果一個成員'workphone is null我需要用homephone替換它。

我會很樂意澄清，如果需要。

Answer 1

select lastname, firstname, 
case when (workphone is null) then homephone else workphone end as workphone 
, homephone 
from members; 

Answer 2

可以使用COALESCE函數，它返回它給了第一個不爲空的說法：

SELECT lastname, firstname, homephone, COALESCE(workphone, homephone) AS workphone 
FROM members