a,b得到表c！！！！！！！！！！！！！！！

[wuxing]

表a:userid username
1 a1
2 a2
3 a3
表b:id1,id2
1 3

我想用sql语句得到表
c：name1 name2
a1 a3

[N_chow]

SELECT b.UserName AS name1,
c.UserName AS name2
FROM b LEFT JOIN a ON b.id1=a.UserID
LEFT JOIN a ON b.id2=a.UserID

[愉快的登山者]

select A.username, C.username from b as B
left join a as A on A.userid = B.id1
left join a as C on C.userid = B.id2