MySQL how to join tables on two fields -

I have two tables with the date and id fields. I want to get involved in both areas. I tried

  Connect to CONCAT (t1.id, t1.date) = CONCAT (t2.id, t2.date)  

This works, but it is very slow, is there a better way of doing this?

  t1.id = t2 on t2 and t1.date = t2.date < / Code>