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 table

table aid val1   a2   b3   c4   atable bval fullforma    appleb    bananac    cat

I would write,

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)

不写在WHERE中是否可以。

Answer 1

你很接近:

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