SQL查询与另一

Question

下面的代码产生一个错误替换表的记录：

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

我想从一个名为members表中选择lastnames，firstnames和你的电话号码。如果一个成员'workphone is null我需要用homephone替换它。

我会很乐意澄清，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函数，它返回它给了第一个不为空的说法：

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