MYSQL比较LEFT JOIN中的多个值

Question

如何比较左连接中的多个值？

我有两张桌子

table a
id val
1   a
2   b
3   c
4   a

table b
val fullform
a    apple
b    banana
c    cat

我会写，

select a.id, b.fullform from a left join b on a.val=b.val

我假设它将加入a = a或b = b

我想这样比较，

select a.id, b.fullform from a left join b on a.val in (a,b)

是否可以不在WHERE中写出来。

Answer 1

你很亲密：

select a.id, b.fullform from a left join b on a.val = b.val
where a.val in (a,b)