Join between tables in two different databases?
Yes, assuming the account has appropriate permissions you can use:
SELECT <...>
FROM A.table1 t1 JOIN B.table2 t2 ON t2.column2 = t1.column1;
You just need to prefix the table reference with the name of the database it resides in.
SELECT <...>
FROM A.tableA JOIN B.tableB
SELECT *
FROM A.tableA JOIN B.tableB
or
SELECT *
FROM A.tableA JOIN B.tableB
ON A.tableA.id = B.tableB.a_id;