Is it possible to fire a mysql trigger for both the insert and update events of a table?
I know I can do the following
CREATE TRIGGER my_trigger
AFTER INSERT ON `table`
FOR EACH ROW
BEGIN
.....
END //
CREATE TRIGGER my_trigger
AFTER UPDATE ON `table`
FOR EACH ROW
BEGIN
.....
END //
But how can I do
CREATE TRIGGER my_trigger
AFTER INSERT ON `table` AND
AFTER UPDATE ON `table`
FOR EACH ROW
BEGIN
.....
Is it possible, or do I have to use 2 triggers? The code is the same for both and I don't want to repeat it.
You have to create two triggers, but you can move the common code into a procedure and have them both call the procedure.
In response to #Zxaos request, since we can not have AND/OR operators for MySQL triggers, starting with your code, below is a complete example to achieve the same.
1. Define the INSERT trigger:
DELIMITER //
DROP TRIGGER IF EXISTS my_insert_trigger//
CREATE DEFINER=root#localhost TRIGGER my_insert_trigger
AFTER INSERT ON `table`
FOR EACH ROW
BEGIN
-- Call the common procedure ran if there is an INSERT or UPDATE on `table`
-- NEW.id is an example parameter passed to the procedure but is not required
-- if you do not need to pass anything to your procedure.
CALL procedure_to_run_processes_due_to_changes_on_table(NEW.id);
END//
DELIMITER ;
2. Define the UPDATE trigger
DELIMITER //
DROP TRIGGER IF EXISTS my_update_trigger//
CREATE DEFINER=root#localhost TRIGGER my_update_trigger
AFTER UPDATE ON `table`
FOR EACH ROW
BEGIN
-- Call the common procedure ran if there is an INSERT or UPDATE on `table`
CALL procedure_to_run_processes_due_to_changes_on_table(NEW.id);
END//
DELIMITER ;
3. Define the common PROCEDURE used by both these triggers:
DELIMITER //
DROP PROCEDURE IF EXISTS procedure_to_run_processes_due_to_changes_on_table//
CREATE DEFINER=root#localhost PROCEDURE procedure_to_run_processes_due_to_changes_on_table(IN table_row_id VARCHAR(255))
READS SQL DATA
BEGIN
-- Write your MySQL code to perform when a `table` row is inserted or updated here
END//
DELIMITER ;
You note that I take care to restore the delimiter when I am done with my business defining the triggers and procedure.
unfortunately we can't use in MySQL after INSERT or UPDATE description, like in Oracle
Related
I'm trying to remove a row after inserted in a temp table and I get this error:
INSERT INTO `temp_program_counter` (`id`, `program_id`) values (NULL, '275')
Can't update table 'temp_program_counter' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
And here is my trigger:
DELIMITER $$
DROP TRIGGER IF EXISTS `testtemp`$$
CREATE
TRIGGER `testtemp` AFTER INSERT ON `temp_program_counter`
FOR EACH ROW BEGIN
UPDATE `program` SET `view_count`=`view_count`+1;
DELETE FROM `temp_program_counter` WHERE id=new.id;
END;
$$
DELIMITER ;
this table is a temp table that get's data with delay and after receiving must update the main table and be deleted from temp.
thanks for helping in advance.
You probably have already resolved this in some way but I'll post the answer anyway:
You cannot refer to the same table that triggered the trigger in a trigger (or a combination of trigger and stored procedure). This could mean an infinite loop, so sql prevents it by giving that error, resulting in always the same error.
Try BEFORE INSERT
Because, you are trying to delete a record which has just been inserted but may be not yet committed in this session. Hence you are getting the error.
If you use BEFORE INSERT, then all other record in the table with id=new.id would be deleted and the new record will be inserted successfully.
DELIMITER $$
DROP TRIGGER IF EXISTS `testtemp`$$
CREATE
TRIGGER `testtemp` BEFORE INSERT ON `temp_program_counter`
FOR EACH ROW BEGIN
UPDATE `program` SET `view_count`=`view_count`+1;
DELETE FROM `temp_program_counter` WHERE id=new.id;
END;
$$
DELIMITER ;
I'm trying to remove a row after inserted in a temp table and I get this error:
INSERT INTO `temp_program_counter` (`id`, `program_id`) values (NULL, '275')
Can't update table 'temp_program_counter' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
And here is my trigger:
DELIMITER $$
DROP TRIGGER IF EXISTS `testtemp`$$
CREATE
TRIGGER `testtemp` AFTER INSERT ON `temp_program_counter`
FOR EACH ROW BEGIN
UPDATE `program` SET `view_count`=`view_count`+1;
DELETE FROM `temp_program_counter` WHERE id=new.id;
END;
$$
DELIMITER ;
this table is a temp table that get's data with delay and after receiving must update the main table and be deleted from temp.
thanks for helping in advance.
You probably have already resolved this in some way but I'll post the answer anyway:
You cannot refer to the same table that triggered the trigger in a trigger (or a combination of trigger and stored procedure). This could mean an infinite loop, so sql prevents it by giving that error, resulting in always the same error.
Try BEFORE INSERT
Because, you are trying to delete a record which has just been inserted but may be not yet committed in this session. Hence you are getting the error.
If you use BEFORE INSERT, then all other record in the table with id=new.id would be deleted and the new record will be inserted successfully.
DELIMITER $$
DROP TRIGGER IF EXISTS `testtemp`$$
CREATE
TRIGGER `testtemp` BEFORE INSERT ON `temp_program_counter`
FOR EACH ROW BEGIN
UPDATE `program` SET `view_count`=`view_count`+1;
DELETE FROM `temp_program_counter` WHERE id=new.id;
END;
$$
DELIMITER ;
In MySQL I tried to define a trigger like this:
DELIMITER $$
CREATE TRIGGER vipInvite
AFTER INSERT ON meetings
FOR EACH ROW
BEGIN
IF(NOT EXISTS (SELECT * FROM participants
WHERE meetid = NEW.meetid AND pid ='vip'))
THEN
IF(EXISTS(SELECT * FROM meetings WHERE meetid = NEW.meetid AND slot > 16))
THEN
INSERT INTO participants(meetid, pid)
VALUES (NEW.meetid,(SELECT userid
FROM people WHERE people.group = 'tap' GROUP BY invite));
END IF;
END IF;
END $$
DELIMITER ;
Produces this error:
This version of MySQL doesn't yet support 'multiple triggers with the same action time and event for one table.
Is there a way to work around this so I can define multiple triggers?
This error means you already have an AFTER INSERT trigger on meetings table.
If it is the same trigger (meaning vipInvite) that you created earlier and now you want to replace it then you need to drop it first
DROP TRIGGER vipInvite;
DELIMITER $$
CREATE TRIGGER vipInvite
...
END$$
DELIMITER ;
Now if you have some other trigger you have to merge code from both triggers into one, then drop existing trigger, and then create a new one.
To show the list of existing triggers use SHOW TRIGGERS.
SHOW TRIGGERS WHERE `table` = 'meetings';
How to reproduce this error in MySQL:
ERROR 1235 (42000): This version of MySQL doesn't yet support 'multiple
triggers with the same action time and event for one table'
Run the following queries:
DELIMITER //
CREATE TRIGGER mytrigger1 AFTER INSERT ON mytable
FOR EACH ROW
BEGIN
END//
DELIMITER //
CREATE TRIGGER mytrigger2 AFTER INSERT ON mytable
FOR EACH ROW
BEGIN
END//
If you want to hook more than one action onto the same event/table, you will have to cram all of it into one trigger. You could call many stored procedures like this:
DELIMITER //
CREATE TRIGGER mytrigger1 AFTER INSERT ON mytable
FOR EACH ROW
BEGIN
CALL fromulate_the_moobars(NEW.myid);
CALL its_peanut_butter_jelly_time(NEW.myname);
END//
I have created table in Slq yog which was working fine. then i created same on mysql terminal.
this also executes with no error:
DELIMITER $$
CREATE TRIGGER trigger1 AFTER INSERT ON table2 FOR EACH ROW BEGIN
INSERT INTO record VALUES (id,NEW.sent);
INSERT INTO temp values (id,NEW.sent,NEW.pcount,NEW.ncount);
END
$$ DELIMITER ;
But after this when I enter show triggers or any other command it ask for -> no input
so I need to terminate mysql. Then when I check show triggers says Empty set.
Where is the mistake here?
DELIMITER $$
CREATE TRIGGER trigger1 AFTER INSERT ON table2 FOR EACH ROW BEGIN
INSERT INTO record VALUES (id,NEW.sent);
INSERT INTO temp values (id,NEW.sent,NEW.pcount,NEW.ncount);
END
$$
DELIMITER ;
new delimiter must be on another line
Is it possible to fire a mysql trigger for both the insert and update events of a table?
I know I can do the following
CREATE TRIGGER my_trigger
AFTER INSERT ON `table`
FOR EACH ROW
BEGIN
.....
END //
CREATE TRIGGER my_trigger
AFTER UPDATE ON `table`
FOR EACH ROW
BEGIN
.....
END //
But how can I do
CREATE TRIGGER my_trigger
AFTER INSERT ON `table` AND
AFTER UPDATE ON `table`
FOR EACH ROW
BEGIN
.....
Is it possible, or do I have to use 2 triggers? The code is the same for both and I don't want to repeat it.
You have to create two triggers, but you can move the common code into a procedure and have them both call the procedure.
In response to #Zxaos request, since we can not have AND/OR operators for MySQL triggers, starting with your code, below is a complete example to achieve the same.
1. Define the INSERT trigger:
DELIMITER //
DROP TRIGGER IF EXISTS my_insert_trigger//
CREATE DEFINER=root#localhost TRIGGER my_insert_trigger
AFTER INSERT ON `table`
FOR EACH ROW
BEGIN
-- Call the common procedure ran if there is an INSERT or UPDATE on `table`
-- NEW.id is an example parameter passed to the procedure but is not required
-- if you do not need to pass anything to your procedure.
CALL procedure_to_run_processes_due_to_changes_on_table(NEW.id);
END//
DELIMITER ;
2. Define the UPDATE trigger
DELIMITER //
DROP TRIGGER IF EXISTS my_update_trigger//
CREATE DEFINER=root#localhost TRIGGER my_update_trigger
AFTER UPDATE ON `table`
FOR EACH ROW
BEGIN
-- Call the common procedure ran if there is an INSERT or UPDATE on `table`
CALL procedure_to_run_processes_due_to_changes_on_table(NEW.id);
END//
DELIMITER ;
3. Define the common PROCEDURE used by both these triggers:
DELIMITER //
DROP PROCEDURE IF EXISTS procedure_to_run_processes_due_to_changes_on_table//
CREATE DEFINER=root#localhost PROCEDURE procedure_to_run_processes_due_to_changes_on_table(IN table_row_id VARCHAR(255))
READS SQL DATA
BEGIN
-- Write your MySQL code to perform when a `table` row is inserted or updated here
END//
DELIMITER ;
You note that I take care to restore the delimiter when I am done with my business defining the triggers and procedure.
unfortunately we can't use in MySQL after INSERT or UPDATE description, like in Oracle