Converting UTC 12 hour time format to indian time using Mysql - mysql

Question

I am writing an event scheduler in Mysql for generating tickets 3 hour prior to the user travel time. Mysl is installed in server where the server time is in UTC and 12 hour format with 5:30 hour difference with IST time. I have one user whose travel time is 7:30 in the morning, so i need to generate ticket for this user at 4:30 in the morning. I am getting current server time and converting to IST and comparing travel time and current converted time difference is 3 hours. But some how its failing and always ticket creating at 10 am in the morning. Below is my complete event writtent in Mysql,
DELIMITER $$
ALTER EVENT `Auto_Generated_Ticket` ON SCHEDULE EVERY 1 MINUTE STARTS CURRENT_TIMESTAMP ON COMPLETION PRESERVE ENABLE DO BEGIN
DECLARE UserId INT;
DECLARE v_finished INT DEFAULT 0;
DECLARE GetDate DATE DEFAULT DATE(NOW());
/*get all active user's who's tariff enddate is > today and available journeys > 0 and pass-status=4(delivered)*/
DECLARE ActiveUserId CURSOR FOR
SELECT UT.user_id FROM `um.user_trs.tariff` UT
INNER JOIN `um.user` U ON U.user_id=UT.user_id
INNER JOIN `um.user_ps.pass` UP ON UP.user_id=UT.user_id
INNER JOIN `ps.pass` P ON P.pass_id=UP.pass_id
WHERE UT.end_date >=DATE(NOW()) AND UT.available_journeys > 0 AND UT.current_balance>0 AND P.status_id=4
GROUP BY UT.user_id;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_finished=1;
SET #GetTime= DATE_FORMAT(NOW(),'%Y-%m-%d %h:%i:%s %p');
OPEN ActiveUserId;
get_userid:LOOP
FETCH ActiveUserId INTO UserId;
IF v_finished=1 THEN
LEAVE get_userid;
END IF;
SET #StartTime=(SELECT RS.start_time FROM `um.user_rm.route` UR
INNER JOIN `rm.route_schedule` RS ON RS.route_schedule_id=UR.route_schedule_id
WHERE UR.user_id=UserId
ORDER BY ABS( TIMEDIFF( RS.`start_time`, TIME(CONVERT_TZ(#GetTime,'+00:00','+05:30')) ) ) LIMIT 1);
SET #TimeDiff=(HOUR(TIMEDIFF(#StartTime,TIME(CONVERT_TZ(#GetTime,'+00:00','+05:30')))));
/*if time difference between current time and schedule start time is 3 hours then generate ticket for the user for that particular schedule*/
IF (#TimeDiff =3) THEN
/*IF (#TNumber IS NULL) THEN*/
IF NOT EXISTS(SELECT ticket_number FROM `um.user_ts.ticket` WHERE route_id=#RouteId AND route_schedule_id=#RoutScheduleId
AND user_id=UserId AND DATE(date_of_issue)=#ISTDATE) THEN
INSERT INTO `um.user_ts.ticket`
(
`user_id`,`route_id`,`route_schedule_id`,`ticket_number`,`date_of_issue`,`is_cancelled`,
`amount_charged`,`user_tariff_id`,`opening_balance`,`is_auto_generated`
)
VALUES
(
UserId,#RouteId,#RoutScheduleId,#TicketNumber,CONVERT_TZ(UTC_TIMESTAMP(),'+00:00','+05:30'),
FALSE,#PerJourneyCost,#UserTariffId,#TariffCurrentBalance,1
);
END IF;/*end of route and schedule check*/
END IF; /*end of time difference check*/
END LOOP get_userid;
CLOSE ActiveUserId;
END$$
DELIMITER ;
Please let me know if any other way to convert time or any mistake which i am not noticing in the above query.
Regards
Sangeetha

Answer 1

There is a dedicated mysql command to do so. CONVERT_TZ(dt,from_tz,to_tz)
See here https://dev.mysql.com/doc/refman/5.6/en/date-and-time-functions.html#function_convert-tz
From their docs:
CONVERT_TZ() converts a datetime value dt from the time zone given by
from_tz to the time zone given by to_tz and returns the resulting
value
Maybe the warning applies to you ?
Warning
Do not use a downloadable package if your system has a zoneinfo
database. Use the mysql_tzinfo_to_sql utility instead. Otherwise, you
may cause a difference in datetime handling between MySQL and other
applications on your system.
I would break it down to a minimalistic example and see if this works.
Here's how I would do it to test the basics:
Simple example:
SELECT CONVERT_TZ('2016-05-24 12:00:00','GMT','MET');
So you could build a query to determine the timediff like this:
HOUR(TIMEDIFF(
CONVERT_TZ('2016-05-24 12:00:00','GMT','MET'),
'2016-05-24 12:00:00'
))