Multiple databases

[eluser]slowgary[/eluser]
If you need to connect to 2 different database servers, you're doing it the right way. If however, you just need to query across multiple databases on the same server, you don't need to make 2 connections - you can simply prepend the database name to your tables.

Here's an example:

Code:

SELECT * FROM my_database.table1
     WHERE my_database.table1.id = 7


SELECT * FROM other_database.table3
     WHERE my_database.table3.id = 5


// this query looks for criminals from america who have
// fled to switzerland
SELECT * FROM switzerland_db.people_table
     WHERE switzerland_db.people_table.id IN (
          SELECT id FROM
               usa.criminals
     )

There's likely a performance hit to making multiple connections to a database server, so this should really be the best way if you're not connecting to 2 different physical servers.