Can Inter-Database Joins Be Performed Using Fully Qualified Table Names?

Inter-Database Joins: A Possibility with Fully Qualified Table Names

Can we merge data from tables stored in separate databases? Yes, this is achievable within the same server and database management system (DBMS) using the join operation.

Syntax and Example

The join syntax remains the same, but a crucial difference emerges: table names must be fully qualified. For instance, consider databases Db1 and Db2 on the same server, where Db1 contains a table "Clients" with the column "ClientId" and Db2 has a table "Messages" with the same "ClientId" column. To join these tables, use the following query:

SELECT *
FROM Db1.dbo.Clients AS c
JOIN Db2.dbo.Messages AS m ON c.ClientId = m.ClientId

This query will extract all rows from the "Clients" table in Db1 and match them with corresponding rows in the "Messages" table in Db2 based on the "ClientId" column.

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