The current system is buggy, and can be off, so it's going to be completely overhauled:

Time System

Previous time system:

• A query would run every minute
• Executed an update method that would insert players with 1 minute, and on dupe keys would append another minute
• Expensive, depended on errors for input

New proposed time system:

• Player times are grabbed from the table on login
• Timestamps are compared between login/logoff
• Login time is appended to total time, and re-submitted
• Much less queries
• A crash would lead to a loss in playtime (possible solution: hourly updates/fixes)

Event System

Previous event system:

SELECT * FROM `playTime` WHERE (`someTimer`%MINIMUM) <= (MINIMUM+INTERVAL) AND `someTimer` >= MINIMUM

• A query would run every x pre-determined minutes to check the SQL database for times. (in the pseudo-query above, where MINIMUM is a constant for the trigger time, and INTERVAL is the time between checks)
• All results from this would "fire" the event for the relevant players.
• Each event would have an individual Runnable scheduled through the ScheduledExecutorService in the java.util.concurrent package.
• This lead to a single query for each event every INTERVAL minutes

New proposed event system:

• When a player logs on, a single query will grab all their times.
• A new runnable will be scheduled to execute x minutes later, when they would "fire" the event normally
• There will be a runnable per-event, per-player.
• Events would be able to be "overridden" or bypassed via permissions
• No future SQL queries would be needed, and times would be more accurate