It's an extremely bad idea to use two databases, although it's technically possible.
They're not THAT different from each other anyway, so any code should work.
Plus all new code being written in PHP should really be using a generic database interface. I recommend (in order of preference)
- PDO - built into PHP from 5.1.0 +
- PEAR:😃B - can be installed with the pear installer; some versions ship with PHP
- ADODB (NOT Microsoft ADO!!!) - confusing name, and I've not used it - but some people report success.
Anyone using the database-specific interfaces is just being silly.
Mark