Multiple databases in Drupal

Have to say, while MDB2 has the more straightforward way of accessing multiple databases (just create more database objects using MDB2::factory()), drupal’s way of doing things is a long way from horrible.

To initialise:
[ccN lang=”php”]$db_url[‘default’] = ‘mysql://drupal:drupal@localhost/drupal’;
$db_url[‘mydb’] = ‘mysql://user:pwd@localhost/anotherdb’;
$db_url[‘db3’] = ‘mysql://user:pwd@localhost/yetanotherdb’;[/cc]
And then to use:
[ccN lang=”php”]db_set_active(‘mydb’);
db_query(‘SELECT * FROM table_in_anotherdb’);
//Switch back to the default connection when finished.
db_set_active(‘default’);[/cc]

Quite straightfoward looking. Now to see if it actually works! 🙂

5 comments

  1. And of course it does, but there are some caveats – you should call db_set_active(‘default’) immediately on finishing your db_query() call or calls, as a few drupal functions access things in the main database and calling l() can cause all manner of fun errors if you’ve not switched back yet.

  2. Hi,
    Is it possible to allow drupal to access different databases? One MySQL and one postgreSQL?

  3. I don’t see why not, just use the DSN to specify one as a mysql:// database and the other as a postgres:// database.

  4. Hi,
    It states here http://drupal.org/node/18429

    This only works with two databases of the same type. For example the following code will not work.

    Are you proposing a different process?

  5. No, my error, I missed that caveat.

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