How can I join databases on different servers in MySQL and MS SQL Server?

Using FEDERATED Storage Engine and Linked Servers to Join Databases on Different Servers

In MySQL, you can connect to multiple databases on different servers and perform joins between them. This can be achieved using either the FEDERATED Storage Engine or by using linked servers in another DBMS, such as MS SQL Server.

FEDERATED Storage Engine

The FEDERATED Storage Engine allows you to create a virtual table that references tables on other servers. To use FEDERATED, you need to create a foreign data wrapper that specifies the connection parameters for the remote server. Once you have created the foreign data wrapper, you can create a federated table that references the remote table. The federated table can then be used in queries just like any other table.

Here is an example of how to create a federated table:

CREATE FOREIGN DATA WRAPPER my_wrapper
  OPTIONS (
    HOST 'server2',
    PORT '3306',
    USER 'username',
    PASSWORD 'password'
  );

CREATE FOREIGN TABLE my_table
  (
    id INT,
    name VARCHAR(255)
  )
  SERVER my_wrapper
  OPTIONS (
    TABLE_NAME 'my_table'
  );

Once the federated table has been created, you can use it in queries just like any other table:

SELECT * FROM my_table;

Linked Servers in MS SQL Server

If you are using MS SQL Server, you can use linked servers to connect to other databases on different servers. Linked servers allow you to execute queries against remote tables as if they were local tables.

To create a linked server, use the sp_addlinkedserver stored procedure:

EXEC sp_addlinkedserver
  @server = 'server2',
  @srvproduct = 'MySQL'

Once the linked server has been created, you can use it in queries just like any other server:

SELECT * FROM server2.my_database.dbo.my_table;

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