one of my client asking me to do property listing website, he want do integrate his oracle database to this website, but i don't have any idea about Oracle, is it possible to integrate oracle r12 database with PHP? any suggestions, tutorials, and examples will be highly-appreciated.
As @APC noted, Oracle has good documentation on using PHP with an Oracle database. However, you'll want to be very security conscious when connecting to the E-Business Suite database. The hosts for the R12 instance will have an experienced DBA you can work with on access that does not compromise security to the EBS.
We are using PHP with oracle for 10 years now, it's not so bad :-) PHP has oci driver implementation, in new PHP it's OCI8 I think.
Best manual about PHP -> oracle is here http://www.oracle.com/technetwork/topics/php/underground-php-oracle-manual-098250.html.