Following is the tutorial to install oracle on xampp with php
Step 1:
download "Instant Client Package - Basic Lite" package from this link
Step 2:
Unzip the package into a location such as: "C:\instantclient_11_2"
Step 3:
add "C:\instantclient_11_2" to PATH of windows environment variable
Step 4:
download these dll packages from here and paste these dlls on php/ext directory
Step 5:
add these lines to php.ini
extension=php_oci8.dll
extension=php_oci8_11g.dll
Step 6:(optional) if you dont have MDB2 already installed type these command on command
pear install MDB2
pear install MDB2_Driver_oci8
Restart Apache and you are done