Data processing is essential for any data-driven application. Whether you access database data or modify it, you perform data processing in one way or another. While in simple cases, data processing may involve a few steps, more sophisticated solutions typically perform multiple operations on the data, with branch logic based on the success or failure of any single operation involved.
For most PHP/Oracle applications, data processing takes place partly at the web/PHP server and partly at the Oracle database server. Even if you are dealing with an application that simply outputs the results of a query, you will need to perform at least two general steps: retrieve data from the database and then display the results to the user. In this case, the database server processes the query, producing the results, and the web/PHP server is responsible for formatting and displaying the query results. In more complex cases, you may have to perform some additional processing...