Example of ALTER Event MySql statement :

CREATE EVENT myevent
ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 1 HOUR
DO
UPDATE myschema.mytable SET mycol = mycol + 1;

CREATE EVENT e_hourly ON SCHEDULE EVERY 1 HOUR COMMENT 'Clears OUT sessions table EACH hour. ' DO DELETE FROM site_activity.sessions;

delimiter |
CREATE EVENT e_daily
ON SCHEDULE
EVERY 1 DAY
COMMENT 'Saves total number of sessions THEN clears the table EACH day'
DO
BEGIN
INSERT INTO site_activity.totals (time, total)
SELECT CURRENT_TIMESTAMP, COUNT(*)
FROM site_activity.sessions;
DELETE FROM site_activity.sessions;
END |
delimiter ;

delimiter |



CREATE EVENT e
ON SCHEDULE
EVERY 5 SECOND
DO
BEGIN
DECLARE v INTEGER;
DECLARE CONTINUE HANDLER FOR SQLEXCEPTION BEGIN END;
SET v = 0;
WHILE v < 5 DO
INSERT INTO t1 VALUES (0);
UPDATE t2 SET s1 = s1 + 1;
SET v = v + 1;
END WHILE;
END |
delimiter ;

CREATE EVENT e_call_myproc
ON SCHEDULE
AT CURRENT_TIMESTAMP + INTERVAL 1 DAY
DO CALL myproc(5, 27);

Example of Mysql ALTER EVENT

CREATE
[DEFINER = { user | CURRENT_USER }]
EVENT
[IF NOT EXISTS]
event_name
ON SCHEDULE schedule
[ON COMPLETION [NOT] PRESERVE]
[ENABLE | DISABLE | DISABLE ON SLAVE]
[COMMENT 'comment']
DO sql_statement;

schedule: AT timestamp [+ INTERVAL interval] ... | EVERY INTERVAL [STARTS timestamp [+ INTERVAL interval] ...] [ENDS timestamp [+ INTERVAL interval] ...]

CREATE
[DEFINER = { user | CURRENT_USER }]
EVENT
[IF NOT EXISTS]
event_name
ON SCHEDULE schedule
[ON COMPLETION [NOT] PRESERVE]
[ENABLE | DISABLE | DISABLE ON SLAVE]
[COMMENT 'comment']
DO sql_statement;

schedule:
AT timestamp [+ INTERVAL interval] ...
| EVERY INTERVAL
[STARTS timestamp [+ INTERVAL interval] ...]
[ENDS timestamp [+ INTERVAL interval] ...]