Backing up your database in Phpmyadmin is accomplished by doing the following:
Step-1:
Click on the databases once you have logged into the Plesk panel.
Step-2:
Upon selecting the database click on phpmyadmin.
Step-3:
Once you reach phpmyadmin click on the export tab.
Step-4:
Check the radio button " Quick - display only the minimal options " and click on "Go".
That's it!! Done.