MySQL如何连接两个字段上的表
我有两个带有 date 和 id 字段的表.我想加入这两个领域.我试过
I have two tables with date and id fields. I want to join on both fields. I tried
JOIN t2 ON CONCAT(t1.id, t1.date)=CONCAT(t2.id, t2.date)
可以，但是速度很慢.有没有更好的方法来做到这一点?
that works, but it is very slow. is there a better way to do this?
推荐答案
JOIN t2 ON t1.id=t2.id AND t1.date=t2.date
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