Since some people had problems with mysql, I changed a few things: a new database will be created and data will be saved differently.
https://github.com/R3fleXi0n/BungeeOnlineTime/commit/873587dd251e71aad66c7ec3ed197dbf2a707427

I AM USING A NEW MYSQL TABLE, SO ALL ONLINETIMES WILL BE RESET.
IF YOU WANT TO IMPORT YOUR OLD DATA, YOU SHOULD ACHIEVE THAT BY EXECUTING THE FOLLOWING MYSQL UPDATE: "INSERT INTO bungeeonlinetime SELECT UUID, OnlineTime FROM onlineTime GROUP BY UUID;"