Mysql:如何在构造OF()中发送两个参数

Question

我想在查询中设置两个条件，但是查询不起作用。

SELECT IF((I.num_ip <> '100.100.100.100') &&
  (I.num_ip <> '100.100.100.101'), I.num_ip, null) AS num_ip 
FROM company C, computers
WHERE C.id_ip = I.id_ip 
AND C.date_conn = '2015-08-12'
GROUP BY num_ip

Answer 1

也可以使用CASE表达式以其他方式编写

Select case when I.num_ip not in ('100.100.100.100', '100.100.100.101')
then  I.num_ip else null end) as num_ip 
From company C
join computers I on C.id_ip = I.id_ip 
Where C.date_conn = '2015-08-12';

** 不确定为什么在这里需要 GROUP BY。