从两个表中查询一个语句？

Question

我有2张桌子

User
-userid
-group
//other unrelated columns

Logs
-userid
-ip

我想要做的是使用IP查询所有用户ID的Logs表，然后获取所有userid的组。单个查询可以实现吗？如果没有，那么除了用userid查询每个用户行之外还有加速吗？

Answer 1

这样的东西？

SELECT ip, userid, group
FROM Logs INNER JOIN User ON Logs.userid = User.userid
WHERE ip = '1.2.3.4'

Answer 2

当然这是一个简单的连接？

select logs.userid,logs.ip,user.group
from logs
left join user on logs.userid=user.userid

Answer 3

select distinct group 
from user u
join logs l on u.userid=l.userid
where l.ip='yourIP'

Answer 4

您应该可以通过加入（http://dev.mysql.com/doc/refman/5.0/en/join.html）

来实现

select User.group
from Logs
   inner join User on Logs.userid = User.userid
where Logs.ip = 'IP';

Answer 5

至少回溯一些作为关键字（组）或可能是特殊（用户）的字段名称

SELECT L.`group`
FROM Logs L
INNER JOIN `User` U ON U.userid = L.userid
WHERE L.ip = '1.2.3.4'
GROUP BY L.`group`