getting message: oci_execute(): ORA-00942: table or view does not exist

Your database config is wrong, please read this article.

Codeigniter Oracle PDO-oci

You have all of your code above the CI database code but it is still using the default.

thanks a bunch for your valuable time, I failed to understand, I followed a online tutorial and I don't know about the differences between oci8 and pdo-oci, this is what for I have uploaded files here. I want to use oracle recommended oci8 but if you seniors recommend I will use pdo-oci, I will check with it and give feedback. 

regards

EDIT: checked your link and I have tested with it "dsn" entry in database.php but it was not working, the dbdriver entry has oci8 or i misunderstood it?