從兩個表中查詢一條語句？

Question

我有2個表

User 
-userid 
-group 
//other unrelated columns 

Logs 
-userid 
-ip

我要的是使用IP查詢日誌表的所有用戶ID做，然後讓所有的用戶ID的組。這可能與一個單一的查詢？如果不是，那麼加速它，而不是用userid查詢每個用戶行？

Answer 1

像這樣？

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

Answer 2

當然這是一個簡單的連接？

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

你應該能夠做到這一點的一個連接（http://dev.mysql.com/doc/refman/5.0/en/join.html）

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

Answer 5

至少背打勾一些是關鍵字（組）或可能是特殊的字段名稱（用戶）

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`