Question

I want to do:

 select column1
 from db1.table1
 where db1.table1.column2 = db2.table2.column1.

In this case, the error message is:

unknown column: db2.table2.column1

My setting for the database 1 and 2 is correct, just don’t know how to write the query in this case.

Answer 1

select t1.column1
from db1.table1 t1
join db2.table2 t2 on t1.column2 = t2.column1

You’ll notice that this query uses the more modern, and preferable, join table on condition syntax