Establishes a connection between PHP and an Oracle database with the given username and password.
Connections can be made using SQL*Net by supplying the TNS name to user like this:
If you have character data with non-ASCII characters, you should make sure that NLS_LANG is set in your environment. For server modules, you should set it in the server's environment before starting the server.
Returns a connection index on success, or false on failure. Details about the error can be retrieved using the ora_error() and ora_errorcode() functions.