I have a trigger as follows:
DELIMITER //
create trigger highStockInsert
After insert on inventory
for each row Begin
if new.currentStock > 250 then Insert INTO higherStockList VALUES (new.prodName, new.StockCount, new.storeName, 'High Alert');
end if; end
// ;
Now when this trigger is act upon I would like mysql to give a message of some sorts, I was messing around with SQLSTATE but if this is triggered the table doesn't update it just blocks the whole insert statement from going through. I was wondering if its possible for the new row to be added but still give off a notification. I was looking if its possible to trigger a warning but found no luck either.
Thanks!
Related
I created some triggers to make some simple validations. I covered the before insert scenario, for example:
CREATE TRIGGER TR_before_insert_login
BEFORE INSERT ON login
FOR EACH ROW
BEGIN
IF (CHAR_LENGTH(NEW.password) < 4 OR CHAR_LENGTH(NEW.password) > 10) THEN
SIGNAL SQLSTATE '42000'
SET MESSAGE_TEXT = 'password must be between 4 e 10 characters';
END IF;
......
But if the user performs an update I can't prevent it from entering incorrect data. Do I need to create a before update and duplicate my validation code or there is a better way to do this.
Why don't put the logic (your validation code) into procedure and execute it inside the separate triggers (insert/update).
-- pseudo code
create procedure PASSWORD_VALIDATION(_psswd) { /* validation */ };
create trigger table_ub BEFORE UPDATE { CALL PASSWORD_VALIDATION(NEW.password);};
create trigger table_ib BEFORE INSERT { CALL PASSWORD_VALIDATION(NEW.password);};
Thus, your validation code is not duplicated.
ALTER TRIGGER [dbo].[trigger_name]
ON [dbo].[table_name]
FOR DELETE, INSERT, UPDATE
AS
BEGIN
'your code here'
END
you can use structure like this to call same trigger for insert,update and delete
I just switched from using Apache's Derby Database to MySQL and still getting familiar with the syntax. I read the documentation about triggers and I think I followed the syntax correctly. However, I'm having problems with BEGIN and END My insert trigger below doesn't work if I put BEGIN and ENDI even tried putting DELIMITER but it doesn't fix it.
CREATE TRIGGER COPY_INSERTED_USERID_TO_ALLUSERS_PERMISSIONS
AFTER INSERT ON ALLUSERS
FOR EACH ROW
BEGIN
INSERT INTO ALLUSERS_ADMIN_PERMISSIONS(USERID)
VALUES(NEW.USERID);
END;
Removing the BEGIN and END makes it work but I'm not able to take full advantage of the compound statements.
CREATE TRIGGER COPY_INSERTED_USERID_TO_ALLUSERS_PERMISSIONS
AFTER INSERT ON ALLUSERS
FOR EACH ROW
INSERT INTO ALLUSERS_ADMIN_PERMISSIONS(USERID)
VALUES(NEW.USERID);
I'd appreciate any help.
Thanks.
Edited:
I tried to follow #Ilanatos advice which works but returns an error on first attempt. I had to refresh the phpmyadmin page to get rid of the error.
Below are the screenshots.
then if I refresh the page(both Firefox and Chrome), I see the trigger.
I don't think it should return an error message during execution of create trigger definition.
Try using the delimiter function when creating your trigger.
DELIMITER $$
CREATE TRIGGER COPY_INSERTED_USERID_TO_ALLUSERS_PERMISSIONS
AFTER INSERT ON ALLUSERS
FOR EACH ROW BEGIN
INSERT INTO ALLUSERS_ADMIN_PERMISSIONS(USERID)
VALUES(NEW.USERID);
END$$
DELIMITER ;
CREATE TRIGGER backupFIDE AFTER UPDATE ON player
FOR EACH ROW
BEGIN
IF (OLD.FIDERating <> NEW.FIDERating) THEN
INSERT INTO playerbackup(PlayerName, OldFIDERating, NewFIDERating)
VALUES(OLD.PlayerName, OLD.FIDERating, NEW.NewFIDERating)
END;
Hi guys, receiving syntax error at line 6 for some reason, been looking online for solution to what might be the cause. Basically looking a simple trigger, that will copy a change change of FIDERating in Player table to a backup table containing OldFIDERating before it was changed, and the NewFIDERating along with the date change was made.
DELIMITER //
CREATE TRIGGER backupFIDE AFTER UPDATE ON player
FOR EACH ROW
BEGIN
IF NEW.FIDERating <> OLD.FIDERating
THEN
INSERT INTO playerbackup(PlayerName, OldFIDERating, NewFIDERating)
VALUES(OLD.PlayerName, OLD.FIDERating, NEW.NewFIDERating);
END IF;
END;
//
DELIMITER ;
I'm trying to find a way to check ,before adding a new tuple in a table, if the tuple respect some condition and in case of one of the conditions is not respected do not allow the insert.
I've thought of something like
DELIMITER //
CREATE TRIGGER t BEFORE INSERT ON Table
FOR EACH ROW
CALL CHECK1(…);
CALL CHECK2(…);
CALL CHECK3(…);
//
DELIMITER;
Where check1,check2,check3 are procedures that raise an exception if the NEW.(attributes) that I pass do not respect condition in the inserting table and/or with other tables.
Is this a correct and/or good way to make what I'm trying to do?
What is the best way to do that?
The best way to do it, is to do the data validation using stored procedures, instead of triggers. The trigger strategy is useful if you only want to filter incoming data. If the objective is to cancel an operation entirely when data values are unsuitable, you cannot do this in MySQL using a trigger.
I'm answering to reply(with a comment my answer would be incomprehensible) and to give more details:
I've used 2 strategies to make my goal, here 2 examples
1)if the check is easy
DELIMITER $$
create trigger RV5_1 before insert on Customer
for each row begin
IF(DATEDIFF(CURDATE(),NEW.birthdate)/365<18)
THEN
SIGNAL sqlstate '45006' set message_text = "too young to be a customer";
END IF;
END;
$$
DELIMITER ;
2) if the check is not easy and need cursors, variables etc
DELIMITER $$
create trigger T2 before insert on Table
for each row begin
IF (check1(NEW.[_some_attribute/s_]) or
check2(NEW.[_some_attribute/s_]))
THEN
SIGNAL sqlstate '45002' set message_text = "invalid insert";
END IF;
END;
$$;
DELIMITER ;
where check1 and check2 are stored functions that returns 0 if it's ok or 1 if there are problem with the new tuple.
Maybe someone with the same problem will found this helpful.
New to MySql triggers, just learning.
CREATE TRIGGER MyTrigger
AFTER UPDATE ON MyTable
FOR EACH ROW
BEGIN
IF (new.field1 < 0 or new.field1 > 5) THEN
UPDATE new SET new.field1 = old.field1;
END IF;
END;
The goal is to keep the value of field1 the same, if the update puts it outside the range.
However, instead it sets it to 0. What am I doing wrong? How should this code look?
Here is an example that should hopefully get you started:
DELIMITER ~
CREATE TRIGGER `so_13547992_trigger`
BEFORE UPDATE ON `so_13547992`
FOR EACH ROW BEGIN
IF ( NEW.`field1` < 0 OR NEW.`field1` > 5 ) THEN
SET NEW.`field1` = OLD.`field1`;
END IF;
END;
~
Why would it work better? Well first of all your example trigger is recursive, you can't update the same table in a trigger that was triggered by an update.
Second, the new in your UPDATE statement is not a table name, you need to specify one explicitly.
It doesn't appear to be a legit trigger at all, doesn't your server complain when you try to create it? Can you perhaps show actually SHOW CREATE TRIGGER `your_trigger`; to make sure that it's really created and looks like you pasted it above?
Even if your example would would work, you're trying to do an unconstrained update on all rows of your table, not on the ones you're trying to update, you should have a WHERE clause; again, given that issue one and two are taken care of.