DELIMITER $$
CREATE TRIGGER insertTrigger BEFORE INSERT ON `agents`
FOR EACH ROW
BEGIN
DECLARE groupID int;
SET groupID = 0;
SET groupID = (SELECT id FROM `groups` WHERE `id` = NEW.group_id);
IF (groupID != 0) THEN
PRINT 'ID is ' + groupID;
ROLLBACK;
END IF;
END$$
DELIMITER ;
The above trigger is created for checking if the foreign key ID exists in the group table.
1) How do I print error messages in mySQL?
2) ROLLBACK Function doesn't work. It gave me the following error message.
"#1422 - Explicit or implicit commit is not allowed in stored function or trigger."
You can use SIGNAL statement to raise an error with custom message from the trigger.
...
IF (groupID != 0) THEN
SET #msg = CONCAT('ID is ', groupID);
SIGNAL SQLSTATE '02000' SET MESSAGE_TEXT = #msg;
END IF;
...
If you want just warning message, then use SQLSTATE code starting with '01...'.
Related
CREATE TRIGGER maindb.before_acc_update
BEFORE UPDATE
ON maindb.acc FOR EACH ROW
BEGIN
DECLARE errorMessage VARCHAR(255);
DECLARE clientName VARCHAR(100);
SET clientName = (select USER());
SET errorMessage = CONCAT('DB Error=> new acc_name value (',
NEW.acc_name,
') cannot be null or empty. Old Value is:',
OLD.acc_name);
IF new.acc_name is null or TRIM(COALESCE(new.acc_name , '')) = '' THEN
BEGIN
INSERT INTO maindb.acc_log_error (old_tz, new_tz, username) values (old.acc_name , new.acc_name, clientName);
END ;
SIGNAL SQLSTATE '23000' SET MESSAGE_TEXT = errorMessage;
END IF;
END;
Mysql cancels my transaction. I'd like to log to maindb.acc_log_error and raise my custom error.
Sorry, if you raise a signal in a trigger, it aborts the action of that trigger, including all changes made by that trigge, e.g. your INSERT into the log table.
The only way you could keep the insert to the log table after the trigger aborts is to do that INSERT as a separate statement before or after your UPDATE to acc that spawned the trigger.
The database is about exam scheduling and this is the main stored procedure which is about scheduling courses on a given date.
I created the procedure but when I try to call it says the procedure is not found.
I've looked through the code but can't find syntax errors, the procedure itself does not have compilation errors, (but that may be because I have to use delimiters?)
DELIMITER $$
CREATE PROCEDURE schedule_course(IN in_code CHAR(3), IN in_date DATE)
BEGIN
DECLARE complete BOOLEAN DEFAULT FALSE;
DECLARE module_code CHAR(3);
DECLARE module_c CURSOR FOR
SELECT course_code FROM module WHERE course_code = in_code;
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET complete = TRUE;
IF (DAYOFWEEK(in_date) = 6 OR 7) THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE TEXT = 'Cannot schedule start date on a weekend'
END IF;
OPEN module_c;
mainloop : LOOP
FETCH NEXT FROM module_c INTO module_code;
IF complete THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE TEXT = 'Something something'
END IF;
INSERT INTO SESSION (`code`, `date`, room)
VALUES
(module_code, in_date, NULL)
LEAVE mainloop;
END LOOP;
DELIMITER ;
CALL schedule_course(WSD, CURDATE())
Error Code: 1305. PROCEDURE cameron.schedule_course does not exist
Mysql 8 show a lot of errors.
I corrected them, the logic is sound but of course you have to check it,
DELIMITER $$
CREATE DEFINER=`root`#`localhost` PROCEDURE schedule_course(IN in_code CHAR(3), IN in_date DATE)
BEGIN
DECLARE complete BOOLEAN DEFAULT FALSE;
DECLARE module_code CHAR(3);
DECLARE module_c CURSOR FOR
SELECT course_code FROM module WHERE course_code = in_code;
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET complete = TRUE;
IF (DAYOFWEEK(in_date) = 6 OR DAYOFWEEK(in_date) = 7) THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'Cannot schedule start date on a weekend';
END IF;
OPEN module_c;
mainloop : LOOP
FETCH NEXT FROM module_c INTO module_code;
IF complete THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'Something something';
END IF;
INSERT INTO SESSION (`code`, `date`, room)
VALUES
(module_code, in_date, NULL);
LEAVE mainloop;
END LOOP;
CLOSE module_c;
END;
DELIMITER ;
seems you have not an end (END $$)
DELIMITER $$
CREATE PROCEDURE schedule_course(IN in_code CHAR(3), IN in_date DATE)
BEGIN
DECLARE complete BOOLEAN DEFAULT FALSE;
DECLARE module_code CHAR(3);
DECLARE module_c CURSOR FOR
SELECT course_code FROM module WHERE course_code = in_code;
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET complete = TRUE;
IF (DAYOFWEEK(in_date) = 6 OR 7) THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE TEXT = 'Cannot schedule start date on a weekend'
END IF;
OPEN module_c;
mainloop : LOOP
FETCH NEXT FROM module_c INTO module_code;
IF complete THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE TEXT = 'Something something'
END IF;
INSERT INTO SESSION (`code`, `date`, room)
VALUES
(module_code, in_date, NULL)
LEAVE mainloop;
END LOOP;
END $$
DELIMITER ;
I need to use trigger to check my Update (SalesQty <> 0) but I cannot get it to work
# TRIGGER - SalesQty has to be bigger than zero
DELIMITER //
CREATE TRIGGER checkzeros BEFORE UPDATE ON Sales
FOR EACH ROW
BEGIN
IF NEW.SalesQty > 0 THEN
CALL updating(0,'P10005',6565990);
ELSEIF
CALL ('Value Has to be Zero') # not sure how to display error msg
END IF;
END//
DELIMITER ;
# PROCEDURE TO UPDATE
DELIMITER //
CREATE PROCEDURE updating(IN SQT INT, IN PID Varchar(10), IN SID INT)
BEGIN
UPDATE Sales SET SalesQty = SQT WHERE ProductID = PID AND SalesID = SID;
END//
DELIMITER ;
CALL updating(1,'PR10005',6565990); # some sort of recursive error here
I'd appreciate any help
Of course there's a recursion when you update the triggered table within the trigger:
IF NEW.SalesQty > 0 THEN
CALL updating(0,'P10005',6565990);
Instead use NEW.SalesQty and OLD.SalesQty
SET NEW.SalesQty = 0;
Your logic looks strange at all. It says: If quantity is less than or equal to zero, indicate an error. However, you try to force CALL updating(0,'P10005',6565990); (quantity = 0) otherwise.
You might just want to SIGNAL an exception when NEW.SalesQty = 0 or NEW.SalesQty < 1.
CREATE TRIGGER checkzeros BEFORE UPDATE ON Sales
FOR EACH ROW
BEGIN
IF NEW.SalesQty < 1 THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'Quantity must not be below 1';
END IF;
END//
This is my trigger for show error handling :
DELIMITER //
CREATE TRIGGER NOTA_PENJUALAN_INS BEFORE INSERT ON nota_penjualan FOR EACH ROW
BEGIN
DECLARE VDATE DATETIME;
If (NEW.INVENTORY_OUT_ID IS NOT NULL) then
CALL STATUS_INV_OUT(NEW.INVENTORY_OUT_ID);
SELECT (a.DOCUMENT_DATE) INTO VDATE
FROM inventory_out a
INNER JOIN NOTA_PENJUALAN b ON a.INVENTORY_OUT_ID=b.INVENTORY_OUT_ID
WHERE b.NOTA_PENJUALAN_ID=NEW.NOTA_PENJUALAN_ID;
End IF;
IF(VDATE > NEW.DOCUMENT_DATE) THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'sorry can not exceed the date that has been specified';
END IF;
END
//
It displays:
And does not display my ShowMessage.
I have simple project for database classes there i have shop database which implement such logic: for each customer in order table we have order with type = 'CART' when customer confirm his order his order change it type to 'ORDER' and we create a new CART for our customer.
Now i want to write trigger that allows me to control that each customer has only one CART.
I write something like this
DELIMITER $$
USE `newshop`$$
CREATE
DEFINER=`root`#`localhost`
TRIGGER `newshop`.`cart_check`
BEFORE INSERT ON `newshop`.`order`
FOR EACH ROW
BEGIN
DECLARE msg VARCHAR(255);
DECLARE count_pn INTEGER;
SELECT count(*) INTO count_pn FROM newshop.order
where newshop.order.type = NEW.type
and NEW.user_id = newshop.order.user_id
and NEW.type = 'CART'
or NEW.type = 'cart'
LIMIT 1;
if count_pn > 0 THEN
BEGIN
set msg = 'Oh no';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
end;
ELSE
BEGIN
set msg = 'Oh yeah';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
END;
END IF;
END$$
then when i try to insert into table new order with type cart for user with id = 1, that already has a cart - this trigger doesn't allow me to do this and if i try to add a cart for another user, that doesn't have cart - this trigger also doesn't allow me to do this.
In else, you also have the SIGNAL SQLSTATE=45000, which is unhandled exception, it will cause return as failed.
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;