Can we use join for two different database tables?

SQL Server allows you to join tables from different databases as long as those databases are on the same server. The join syntax is the same; the only difference is that you must fully qualify table names.

Let’s suppose you have two databases on the same server – Db1 and Db2. Db1 has a table called Clients with a column ClientId and Db2 has a table called Messages with a column ClientId (let’s leave asside why those tables are in different databases).

Now, to perform a join on the above-mentioned tables you will be using this query:

select *
from Db1.dbo.Clients c
join Db2.dbo.Messages m on c.ClientId = m.ClientId