In a Plesk 9 environment – go to Domains >> the domain you’re looking to backukp the database for >> Databases >> Webadmin

This will launch phpMyAdmin web based MySql interface.

Choose the database for the WordPress installation that is being backed up.

Click on the Export Tab

back-phpadmin

 

Check Add DROP TABLE in Structures,  Complete inserts in Data and Save as file with None for compression

 

back-phpadmin2 

The file will download to you computer

back-phpadmin3

 

A more detailed offical instruction set can be found here.

http://codex.wordpress.org/WordPress_Backups