how to connect two tables of two different Database

Question

hi, assume that we have 2 database:- DB1 and DB2 in Db1 there are few tables and also in DB2 there are few tables in Db1 there is one table named tbl101 and in DB2 there is one table named tbl303 now i want to connect this two tables: tbl101 and tbl303 how that can be achieved? what is the code?