During the installation of Magento you have the option to use a database prefix for your Magento tables in the database. Using such a database prefix adds to the security of your site, because generic SQL Injection attacks will be more likely to fail. But if you installed Magento using the demo-data or if you forgot about this thing during installation, you are stuck with a database without prefix. Here is the procedure to update your Magento instance with a different prefix.
Renaming all database tables
Renaming database tables could be done manually through a tool like phpMyAdmin, but because a default Magento install counts over 200 tables, this task is better performed by using a PHP-script. Open up a file and add the following PHP-code to it:
Make sure these settings match your own Magento installation. The $database_host is most likely "localhost", but it could be different. Consult your hosting provider for these details, or open up the Magento file app/etc/local.xml which already contains these details.
The settings contain the variable $table_prefix which is set here to "dwz_". The prefix could be changed into something else. We recommend you use only alphabetical characters and end the prefix with an underscore ("_"). These configuration settings are used in the rest of the PHP-script. Add the following PHP-code to the same file:
Save the file to a name like "rename_table_prefix.php" (ending with a ".php" extension) and upload it to your Magento website.
Run the script
Before you run the script you should of course prepare a database backup and a file backup. Also make sure you know how to restore these backups. If you are ready for it, just run the PHP-script by entering the right URL in your browser:
This should rename all the database tables to include the new table prefix. If this went ok, remember to delete the PHP-script afterwards.
Modifying the Magento configuration
Now that the database tables are modified, you will also need to modify the Magento configuration. Open up the file app/etc/local.xmland locate the following line:
Change it to point to the new table prefix:
That's it. It might be that you need to empty out the Magento cache directory (MAGENTO/var/cache) but normally everything should be working right away.