Add value to a column each month in Mysql Data Base

Question

is there a way to update automatically the values of a column in a table in Mysql DB with a predifined value and the update should occur each month.

The situation is

Answer 1

Databases don't really work that way. They are meant for storing information. You can write triggers so if you update a row or insert then an event happens but other then that the data doesn't change

Something like this should be handled in the application logic. Creat a cron or other periodic job that will grab rows created on X date and update them

Answer 2

Consider using mysql's Create Event strategy that can take away from needing to do cron jobs.

DELIMITER $$
CREATE EVENT monthlyAddFlexDaysEvent
ON SCHEDULE EVERY '1' MONTH
STARTS '2015-09-01 00:00:00'
DO 
BEGIN
 update empAccrued set daysAccrued=daysAccrued+2.5;
END$$
DELIMITER ;

---

DELIMITER $$
CREATE EVENT annualThingEvent
ON SCHEDULE EVERY '1' YEAR
STARTS '2016-01-01 00:00:00'
DO 
BEGIN
 -- perform some annual thing
END$$
DELIMITER ;

---

In just about any event you could do something that doesn't fall on say the first of the year. Such as a weekly event that handles updates based on employee anniversary dates.

From the Manual page on CREATE EVENT,

interval:
    quantity {YEAR | QUARTER | MONTH | DAY | HOUR | MINUTE |
              WEEK | SECOND | YEAR_MONTH | DAY_HOUR | DAY_MINUTE |
              DAY_SECOND | HOUR_MINUTE | HOUR_SECOND | MINUTE_SECOND

Properly setting up events to even happen and monitoring them is important.

show variables where variable_name='event_scheduler';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| event_scheduler | OFF   |
+-----------------+-------+

ooops, the event scheduler is not turned on.

Well I can wait all day long, events aren't even turned on

SET GLOBAL event_scheduler = ON;  -- turn her on

show variables where variable_name='event_scheduler';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| event_scheduler | ON    |
+-----------------+-------+

List all events by schema name:

show events from so_gibberish;

or

show events\G; -- <--------- I like this one from mysql> prompt
show events; -- <--------- from workbench / sqlyog


*************************** 1. row ***************************
                  Db: so_gibberish
                Name: set_trips_finished
             Definer: GuySmiley@localhost
           Time zone: SYSTEM
                Type: RECURRING
          Execute at: NULL
      Interval value: 1
      Interval field: MINUTE
              Starts: 2015-08-23 00:00:00
                Ends: NULL
              Status: ENABLED
          Originator: 1
character_set_client: utf8
collation_connection: utf8_general_ci
  Database Collation: utf8_general_ci