Without full outer join when I use mysql as database

Bug reports
1

Metabase version: v0.38.1 mysql version: 5.7.18
37

2

Hi @marcco
MySQL 5.7 does not support full outer joins:
https://stackoverflow.com/questions/4796872/how-to-do-a-full-outer-join-in-mysql
https://www.metabase.com/docs/latest/users-guide/custom-questions.html#joining-data