How can i make the following query execute each hour automatically?
SELECT count(*)
FROM user_tab_columns
WHERE table_name='MYTABLE'
Usually in a DBMS exist some schedule of instrument. In Oracle the instrument is DBMS_SCHEDULER.
MySQL same have scheduler. You should check global variable event_scheduler=1. Then you can create schedule:
CREATE EVENT 'new_event'
ON SCHEDULE EVERY 1 HOUR STARTS CURRENT_TIMESTAMP
ON COMPLETION NOT PRESERVE
ENABLE
COMMENT '' DO
call new_proc();
where new_proc() is procedure with your query.
Related
Say you have a query you want to run on your database, but you know that query is going to take a long time to complete, and you don't have direct access to the machine where MySQL is running, or to some other endpoint which has a stable connection with that machine. What do you do?
Well, you create a one time event that performs the necessary query.
Something like this:
CREATE EVENT <event_name>
ON SCHEDULE
AT CURRENT_TIMESTAMP + INTERVAL 10 SECOND
ENABLE DO
BEGIN
-- log the event started
INSERT INTO EventLogs (`Name`, `Start`, `Query`)
VALUES (<event_name>, CURRENT_TIMESTAMP, <query_string>);
-- run the query
....
... <query>
....
-- log the event done
UPDATE EventLogs
SET `Done` = CURRENT_TIMESTAMP
WHERE `Name` = <event_name>;
END
The above template can handle any arbitrary query.
Sorry, don't really know much about this stuff!
I have a table with a few columns, one of them is called 'expirationday' and every row has its unix timestamp for this column.
I would like to know, if at all possible, how to delete a row when the time in the 'expirationday' column (for that row) is reached.
Please note that it does not need to delete rows accurately to the second, a couple of hours is fine.
script.sh
Create a shell script like this:
#!/bin/bash
mysql --user=[username] --password=[password] --database=[db name] --execute="DELETE FROM tbl_name WHERE expiration_date < NOW()
Create a cron job that executes the (it will run every 30 min)
type
crontab -e
Add:
0,30 * * * * /path/script.sh
It's worth looking at the MySQL event scheduler. You could schedule a job to run for example every half hour.
It could then call a DELETE statement directly or to call a MySQL Function or Procedure.
DELIMITER $$
CREATE
EVENT `deleteExpire`
ON SCHEDULE EVERY 1 HOUR STARTS '2015-01-01 00:00:00'
DO BEGIN
DELETE FROM mytable
WHERE expirationday < UNIX_TIMESTAMP();
END */$$
DELIMITER ;
Also see this for more example usage.
I need to delete rows from table 14 days after the DELETE query has been made. Is it possible to do this using MySQL?
You can use the built-in MySQL Event Scheduler to schedule a query or a stored routine to run at an arbitrary point in time:
This is an example of a minimal CREATE EVENT statement:
CREATE EVENT myevent
ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 1 HOUR
DO
UPDATE myschema.mytable SET mycol = mycol + 1;
Please mind, the Event Scheduler is disabled by default.
Let's say I have rows of information in an SQL database.
I want to have rows of information that are older than 30 days to be automatically removed.
Is this possible?
Additional information:
I am using the SQL date function provided to collect the dates.
This problem has two aspects:
How to schedule
Actual SQL Statement
How to Schedule
You have multiple options, but all of this revolves around whether you will schedule, or whether you will have a stored procedure triggered.
Three options
Use MySql event scheduling: http://dev.mysql.com/doc/refman/5.1/en/events-overview.html
Schedule through an operating system (CRON, SCHEDULED TASK) the execution of an app using SQL (either PHP script, java etc)
Have a trigger that is executes a stored procedure every time a change is made to a table.
I would propose options 1 and 2 are the best.
SQL Statement
The actual SQL statement is quite easy provided you have a field (e.g. dateField) that represents insertDate...
delete from myTable where insertDate < DATE_SUB(NOW(), INTERVAL 1 MONTH);
You can easily generate this value using the NOW() function within an insert statement, for example:
insert into myTable values (NOW(), 'value1', 'value2', ... , 'valueN');
Scheduling Using Event Scheduler at End of Day
If you have the CREATE EVENT privilege this will work through PHP MyAdmin.
See also: http://www.sitepoint.com/how-to-create-mysql-events/
CREATE EVENT `clean_up2`
ON SCHEDULE EVERY 1 DAY STARTS CURRENT_DATE
DO
delete from `data` where updated_on < DATE_SUB(NOW(), INTERVAL 1 MONTH);
END;
Yes. In SQL Server you could create a stored procedure to perform the delete, and create a SQL Agent job that runs every day (or a schedule of your choosing)
Can any one help me how to create an event in MySQL so that it has to be executed for every 10 seconds?
I have tried with the following code but it is inserting only once but when i see whether the event is running of not in process list it is in running state
create event e_insert on schedule at 'timestamp' + interval 1 second do insert into 'table_name' values (now());
You should write -
ON SCHEDULE EVERY '10' SECOND
instead of on schedule at...
Using the Event Scheduler.
Edit:
CREATE EVENT event1
ON SCHEDULE EVERY '10' SECOND
STARTS CURRENT_TIMESTAMP
ON COMPLETION PRESERVE
DO
BEGIN
INSERT INTO...
END
set global event_scheduler = 1;
check this here