How to access Multiple DB2 Relational Databases In A Single Query I am looking for a solution to the problem described below.
There are two DB2 instances with two authorization IDs on the same server and can be accessed using the same user User1.
Example:
To access Inst1DB, I use the following commands:
[User1 ~]$ . /db2/authID1db2/home/authID1db2/sqllib/db2profile
[User1 ~]$ db2 connect to Inst1DB

To access Inst2DB, run the following commands:
[User1 ~]$ . /db2/auth2db2/home/auth2db2/sqllib/db2profile
[User1 ~]$ db2 connect to Inst2DB

Note that one needs to terminate the current DB2 session before connecting to another DB instance.
To terminate DB session, run the following command:
[User1 ~]$ db2 terminate

Issue:
I want to join two tables, one of which belongs to INST1DB and the other to INST2DB, while connected to INST1DB.
[User1 ~]$ . /db2/authID1db2/home/authID1db2/sqllib/db2profile
[User1 ~]$ db2 connect to Inst1DB
[User1 ~]$ db2 &quot;Select * from Inst1DB.schema1.table1 T1 , Inst2DB.schema2.table2 T2 where T1.column1 = T2.column1.

Curerntly I am getting below error:

SQL0204N  &quot;Inst2DB.schema2.table2&quot; is an undefined name.  SQLSTATE=42704.

Query:
Can anyone suggest to me how to connect the two instances and perform a join on these tables?
One way you can achieve this is via federation. In short words, if you want to access db_b from db_a, you catalog db_b in instance of db_a. You then create nicknames in db_a for the tables in db_b that you want to access. The nicknames can with some restrictions be treated as tables, so you can join a table in db_a with a table in db_b.