There is Two way to backup your database
One:Folder backup In windows go to xampp installation folder xampp> mysql > data > here you find your database name folder. copy it and save it .
you can use any other computer just go to xampp installation folder xampp> mysql > data >paste it here.
Note: You should not overwrite the MySql default folders and only overwrite 3 files

    ibdata1
    ib_logfile0
    ib_logfile1

others should remain as default. Thanks otherewise you wont see your databases in PHPMyAdmin. Thanks
Two:export database .sql backup In browser go to phpmyadmin and select your database >then in to the top mane click Export. then write a name in New template input box .then click go .you will find a file is down loaded.
you can use it any other computer then go to phpmyadmin in browser and create a database and on the top menu click Import click choose file > select this file witch is downloaded > then click go button.