Looking for assistance crafting a mysql trigger. My current code does not work as intended. What I would like to do is if field A in table A is modified, copy field A to field B in table A.
Current code looks like this:
BEGIN
IF new.set_id=301 THEN
UPDATE lighting_io_settings SET slider1_val=new.val WHERE set_id=402;
END IF;
END
Obviously it fails because an update is calling an update.
On before update you can check the old tuple value on variable "OLD" and check the new tuple values on "NEW" variable.
BEGIN
IF NEW.columnA != OLD.columnA THEN
//do whatever you want here like
NEW.columnB = NEW.columnA;
//can call update again, just don't change the columnA
update tableA set columnB = NEW.columnA where id = 402;
END IF;
END
Related
I am new to this and cant seem to find a situation similar to mine and Im sure the answer is simple.
I have two columns, one is a predefined licenseplate ("licenseplate") and one that will be a user inputted licenseplate ("enterlicenseplate").
I made a third column which will be the sort of error check column and will have its values inputted by a trigger. Basically if the entered license plate is the same as the predefined licenseplate, set that third column to 0, if the entered license plate is null(not inputted anything yet( set that to 1, and if theres values in both and they dont match, set it 2. But i keep getting script errors. Not sure if its my syntax or im going about this all wrong.
I appreciate any help!
CREATE TRIGGER MatchPlateOnUPDATE
BEFORE UPDATE ON wp_wpdatable_3
FOR EACH ROW
BEGIN
IF (NEW.enterlicenseplate is NULL) THEN
UPDATE wp_wpdatatable_3
SET MatchingPlates = 0;
ELSEIF (NEW.enterlicensplate = New.licenseplate) THEN
UPDATE wp_Wpdatatable_3
SET MatchingPlates = 1;
ELSE UPDATE wp_Wpdatatable_3
SET MatchingPlates = 2;
END
Your problem with the if statement is that you are missing closing end if;.
But there is more: a trigger cannot action the table it was fired upon - and even if it could, then your query would basically update all rows in the table, since your updates have no where clause.
Here, you just need to modify the value of column matchingPlates in the record that is about to be inserted:
delimiter //
create trigger matchplateonupdate
before update on wp_wpdatable_3
for each row
begin
if new.enterlicenseplate is null then
set new.matchingplates = 0;
elseif new.enterlicensplate = new.licenseplate then
set new.matchingplates = 1;
else
set new.matchingplates = 2;
end if;
end;
//
delimiter ;
I'd like to have a tricky SQL statement as an Event that runs every couple of minutes.
Currently, I'm doing so with Java, using 3 separate statements that executing sequentiality in a transaction connection.
Q: I don't know how to construct such an SQL statement without Java. If impossible to have a single SQL statement, I'd like to use transaction (as I'm using in Java) and rollback in case of failure in any of those separate statements.
My Case:
I have 3 tables: "Factory", "Plan", "Machine".
I want to do something as below:
1.
WHERE Machines.annualCheck == "TRUE"
SET Machine.status = "IN_ANNUAL_CHECK"
For machines that got updated I need to do the following:
2.1 Update the related factory
WHERE Factory.id == Machine.linkFactoryID
UPDATE Factory.totalActiveMachines = --1
2.2 Delete the upcoming plans that planned to be handled by the related machine
DELETE rows WHERE Plan.willHandleByMachineID = Machine.ID
p.s. I'm using MySQL
Thank you!
Update:
In following to Simonare suggestion, I tired to do the following:
DELIMITER $
CREATE PROCEDURE annualCheck(IN Machine_ID int, IN Factory_ID int)
BEGIN
UPDATE machine_table
SET machine_table.annualCheck = 'IN_ANNUAL_CHECK'
WHERE machine_table.machine_id = Machine_ID;
UPDATE factory_table
SET factory_table.totalActiveMachines = factory_table.totalActiveMachines - 1
WHERE factory_table.factory_id = Factory_ID;
DELETE FROM plan_table WHERE plan_table.assign_to_machine = Machine_ID
END$
DELIMITER $$
BEGIN
SELECT #m_id = machine_id, #f_id = link_factory_id
FROM machine_table
WHERE machine_table.annualCheck = 'TRUE';
END$$
CALL annualCheck(#m_id,#f_id)
I don't know why, but I'm running into syntax errors - one after the other.
It's my first time to use PROCEDURE and DELIMITER. Am I doing it right?
you can use stored procedure
delimiter //
CREATE PROCEDURE myProc (IN Machine_ID int)
BEGIN
UPDATE myTable
SET Machine.status = "IN_ANNUAL_CHECK"
WHERE Machines.annualCheck == "TRUE";
Update the related factory
WHERE Factory.id == Machine.linkFactoryID
UPDATE Factory.totalActiveMachines = totalActiveMachines -1;
DELETE FROM Plan WHERE Plan.willHandleByMachineID = Machine_ID;
END//
then you can execute it either from mysql
CALL simpleproc(#a);
or from Java
It is also possible to create trigger on the Machine table, something like this:
CREATE TRIGGER `TRG_Machines_AfterUpdate` AFTER UPDATE ON `Machine` FOR EACH ROW BEGIN
IF OLD.annualCheck = 'TRUE' AND NEW.annualCheck = 'IN_ANNUAL_CHECK' THEN
UPDATE
Factory
SET
totalActiveMachines = totalActiveMachines - 1
WHERE
id = NEW.linkFactoryID
;
DELETE FROM
Plan
WHERE
willHandleByMachineID = NEW.ID
;
END;
END
So you can just issue normal update:
UPDATE Machine SET annualCheck = 'IN_ANNUAL_CHECK' WHERE annualCheck = 'TRUE'
I'm trying to get a trigger to run before an update is processed on a per record level of a table.
What I'm trying to do is when an update occurs on a record for the qst_title column, if the column qst_perma_title is NULL then the qst_perma_title column is updated with the value in the qst_title column and the qst_title column is updated as per the original update query.
I'm using the code below but no errors are shown and the column qst_perma_title isn't updated.
The current values are:
qst_title = 'Old Title'
qst_perma_title = NULL
query
UPDATE TD_QUESTION SET qst_title = 'New Title Value' WHERE qst_id = 1;
trigger
DELIMITER //
CREATE TRIGGER TRG_QST_UPD
BEFORE UPDATE ON TD_QUESTION
FOR EACH ROW
BEGIN
IF OLD.`qst_perma_title` IS NULL THEN
SET NEW.`qst_perma_title` = OLD.`qst_title`;
END IF;
END//
DELIMITER ;
CREATE TRIGGER TRG_QST_UPD
BEFORE UPDATE ON TD_QUESTION
FOR EACH ROW
IF OLD.qst_perma_title IS NULL THEN
SET NEW.qst_perma_title = OLD.qst_title;
END IF;
First run this query and then try updating. I checked, it is working fine for me.
I am trying to figure out a conditional trigger for an update to a MySQL table.
The issue is that the update trigger fires off even when the data being entered is the same as the data that was already there. So if I have a column with a row:value set up like this plus_votes:2 if I update with UPDATE votes SET plus_votes = 2; even though nothing has really changed the UPDATE trigger still gets fired off. So to prevent all of this I want to add a conditional clause to my trigger like this
BEGIN
IF NEW.vote_value <> OLD.vote_value THEN
UPDATE my_other_table
SET plus_votes =
CASE NEW.vote_value WHEN '1'
THEN plus_votes + 1
ELSE plus_votes
END,
minus_votes =
CASE NEW.vote_value WHEN '1'
THEN minus_votes
ELSE minus_votes +1
END
WHERE my_other_table.id=NEW.votes_join_id;
END
END
the second half of the issue is that I have CASE condition inside the IF statement.
Can someone help on this issiu and show how to do nested conditionals inside a TRIGGER?
much appreciated
although the syntax you have posted is completely wrong, I have figured out what you want try this ( not tested )
DROP TRIGGER IF EXISTS upd_vote;
DELIMITER $$
CREATE TRIGGER upd_vote AFTER UPDATE ON `my_other_table`
FOR EACH ROW BEGIN
IF NEW.vote_value <> OLD.vote_value THEN
SET
NEW.plus_votes = IF(NEW.vote_value=1,OLD.plus_votes+1,OLD.plus_votes),
NEW.minus_votes = IF(NEW.vote_value=1,OLD.minus_votes,OLD.minus_votes +1 )
END IF;
END$$
DELIMITER ;
im trying to make an trigger that updates a table when i modify another table...
Here is my code:
CREATE TRIGGER updpartido AFTER UPDATE ON partidos
ON EACH ROW
BEGIN
SET #vgls = SELECT vgoles(NEW.eqvis)
SET #lgls = SELECT vgoles(NEW.eqloc)
UPDATE equipos SET gf=#vgls WHERE id=NEW.eqvis
UPDATE equipos SET gf=#lgls WHERE id=NEW.eqloc
END
What it must do is, when i update an match, it must automaticly run this trigger and update the goals.
But it gives me an error.
What im doing wrong? Thanks and have a nice day...!
I notice that you don't have any statement terminators in your trigger, that will generate some complaints because, for example, SET #lgls = SELECT vgoles(NEW.eqloc) UPDATE equipos SET gf=#vgls WHERE id=NEW.eqvis doesn't make any sense. So you need some semicolons in the trigger but you also need to get those semicolons past the parser by temporarily changing the delimiter. You're also using ON EACH ROW when it should be FOR EACH ROW:
delimiter |
CREATE TRIGGER updpartido AFTER UPDATE ON partidos
FOR EACH ROW
BEGIN
SET #vgls = SELECT vgoles(NEW.eqvis);
SET #lgls = SELECT vgoles(NEW.eqloc);
UPDATE equipos SET gf=#vgls WHERE id=NEW.eqvis;
UPDATE equipos SET gf=#lgls WHERE id=NEW.eqloc;
END;
|
delimiter ;