I am trying to setup a trigger so an insert does not occur if a condition is not met.
I thought the below was the way to do it but i am not sure
I am getting an error
/* SQL Error (1407): Bad SQLSTATE: '45000 ' */
Can anyone let me know why I am getting this error and the best way for me to prevent an insert if the condition is not met in mysql.
DELIMITER $$
SHOW WARNINGS$$
USE `warrington_central`$$
CREATE TRIGGER before_insert_image_comment_section_check
BEFORE INSERT ON image_comment FOR EACH ROW
BEGIN
DECLARE error_msg varchar(255);
IF New.section != (SELECT id from section where section = "image")
THEN SET error_msg = "Cannot insert a comment into this section as it is the wrong section type";
SIGNAL SQLSTATE '45000 'SET MESSAGE_TEXT = error_msg;
END IF;
END
$$
SHOW WARNINGS$$
SQLSTATE is required to be a a 5 character string unless previously declared using DECLARE ... CONDITION;
SIGNAL SQLSTATE '45000 'SET MESSAGE_TEXT = error_msg;
You're trying to set SQLSTATE to '45000 ' (note the space) which is 6 characters long. Fix the spacing and you should not see the message again (it is also reflected in your error message, but the space is a bit hard to see)
Related
I have a trigger in MySQL
DELIMITER $$
CREATE TRIGGER trigger2
BEFORE INSERT ON participated FOR EACH ROW
BEGIN
IF((SELECT COUNT(*) FROM participated WHERE driver_id = NEW.driver_id) > 3) THEN
DELETE FROM accident WHERE report_no = NEW.report_no;
SIGNAL SQLSTATE '45000' SET message_text = "Driver is already involved in 3 accciddents";
END IF;
END;$$
DELIMITER ;
First an accident report is inserted into accident table. Before inserting in to participated table if it involves a driver who has participated in more than 3 accident a waring has to be given and driver's data in accident table should be deleted.
'accident' and 'participated' are the two tables.
accident(report_no,date,location);
participated(driver_id,reg_no,report_no,amount);
ex:
insert into accident values(34,"2022-04-05","bangalore");
insert into participated values("D1","KA-09-MM-5644",34,20000);
ERROR 1644 (45000): Driver is already involved in 3 accciddents
Warning is working but it is not deleting the row in accident table. accident table still has the row with report_no 34
The body part in Mysql trigger is like a single ALL-OR-NOTHING transaction. This means every query inside has to be successful, or the entire process is undone. By using SIGNAL SQLSTATE '45000' SET message_text , an error is intentionally raised, which rolls back every thing that has happend so far, and a message is returned. Note, the INSERT statement itself is cancelled due to error induced. Of course, it's possible to ignore the error by declaring a continue handler in the very begining of the trigger.
BEGIN
declare continue handler for SQLSTATE '45000' begin end;
IF((SELECT COUNT(*) FROM participated WHERE driver_id = NEW.driver_id) > 3) THEN
DELETE FROM accident WHERE report_no = NEW.report_no;
SIGNAL SQLSTATE '45000' SET message_text = "Driver is already involved in 3 accciddents";
END IF;
END
This will make sure things keep going after SQLSTATE '45000' is encountered. However, the message_text is IGNORED, as it's only intended to show up to address a warning/error, not for a continue handler. And regrettably, we can not return a result set using a trigger. So if we add a SELECT statement or something alike after the SIGNAL statement , an error will pop up:
select "Driver is already involved in 3 accciddents" as a warning;
-- OR
show warnings;
-- Error Code: 1415. Not allowed to return a result set from a trigger
If we really need a message to show up,we can considering using a procedure to bypass the restriction enforced by trigger:
DELIMITER $$
CREATE TRIGGER trigger2
BEFORE INSERT ON participated FOR EACH ROW
BEGIN
IF((SELECT COUNT(*) FROM participated WHERE driver_id = NEW.driver_id) > 3) THEN
DELETE FROM accident WHERE report_no = NEW.report_no;
SET #warning = "Driver is already involved in 3 accciddents"; -- here we don't really need a SIGNAL statement. Just creating a user variable is adequate.
else set #warning=null;
END IF;
END$$
create procedure insert_participated (d_id varchar(20),rg_no varchar(20),rp_no int,amt int)
begin
insert into participated values(d_id,rg_no,rp_no,amt);
if #warning is not null then
select #warning as warning;
end if;
end $$
DELIMITER ;
By using a procedure ,we can display a message. And if we directly use an insert statement(when we forget to use the procedure), the trigger's operation still applies. Therefore, we might think about adding an INSERT statement to populate an auditing table for future reference.
I am trying to put a constraint on a database where if generic_asset.type = 'raw' then generic_asset.atomic = 1 must be maintained. For this I wrote the following trigger of type BEFORE INSERT. Here is the snippet:
DELIMITER //
CREATE TRIGGER generic_asset_check BEFORE INSERT ON generic_asset FOR EACH ROW
BEGIN
IF NEW.type = 'raw' THEN
BEGIN
IF NEW.atomic = 0 THEN
SET SQLSTATE = 'Sorry cannot insert';
END IF;
END IF;
END //
DELIMITER ;
Error is like:
#1064 - syntax error near 'SQLSTATE = 'Sorry cannot insert';
END IF;
END IF;
END' in line 6
(translated from French).
I tried various syntax but all seam not to work and also knowing that my changes are so little like changing double quotes, removing BEGIN with END IF;... So I know these turns are irreverent.
I revised syntax in many internet resources and official documentation, nothing helped.
MySQL's IF statement does not take a BEGIN keyword. Also, if you want to raise an error from within the trigger, you need SIGNAL. Finally, these two nested conditions can be flattened.
Consider:
DELIMITER //
CREATE TRIGGER generic_asset_check BEFORE INSERT ON generic_asset FOR EACH ROW
BEGIN
IF NEW.type = 'raw' AND NEW.atomic = 0 THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Sorry cannot insert';
END IF;
END //
DELIMITER ;
Demo on DB Fiddle
I want to make a trigger that prevent inserting overlaping dates. For example:
If I have an offer "Oferta" with the date from 1/3/2016 to 5/3/2016, I can't insert a new offer with the date 2/3/2016 to 4/3/2016 or 4/3/2016 to 7/3/2016
My SELECT checks that condition I believe. What I don't know how to do is to make an error if such happens. I'm new to triggers and Im having syntax errors, I checked triggers syntax but couldnt find the problem...
DELIMITER $$
CREATE TRIGGER tri_check_date_overlap BEFORE INSERT ON Oferta
FOR EACH ROW
BEGIN
IF EXISTS(
SELECT * FROM Oferta WHERE
(new.morada = morada AND new.codigo = codigo
AND ((new.data_inicio BETWEEN data_inicio AND data_fim)
OR new.data_fim BETWEEN data_inicio AND data_fim)
)
)
/*CALL raise_application_error(3001, 'Not odd number!'); */
DECLARE msg varchar(255);
set msg = concat('Error: That right is not allowed!', cast(new.right as char));
signal sqlstate '45000' set message_text = msg;
END $$
DELIMITER ;
Your logic is ok, I think you just missed the 'then' condition after 'if' and 'end if' before the end of the trigger.
I'm trying to write a trigger for a table named classes_tbl where I basically want to check before update if the participants are at the maximum, if true - do not allow update, and raise error message.
As well as check if participants = 0 in case the the update table tries to decrease the number, it needs not to be possible to decrease below 0 - and again raise an error message in this case.
I'm not 100% accustomed to MySQL so I'm not sure what is missing or wrong. It would be nice If someone could give me a hint.
Here is my Create Trigger syntax:
DELIMITER //
CREATE TRIGGER MaxBelegt_TRGGR
BEFORE UPDATE ON classes_tbl
FOR EACH ROW
BEGIN
DECLARE
n_count NUMBER(3);
msg varchar(255);
SELECT maxParticipants
INTO n_count
FROM rooms_tbl
WHERE rid = :NEW.rid;
IF :OLD.participants = n_count THEN
set msg = concat('MyTriggerError: MaxParticipants for Room exceeded. On MaxBelegt_TRGGR -> belegtAnz : ', cast(OLD.participants as char));
signal sqlstate '45000' set message_text = msg;
END IF;
IF :NEW.participants < 0 THEN
set msg = concat('MyTriggerError: Participant number already 0. On MaxBelegt_TRGGR -> belegtAnz : ', cast(OLD.participants as char));
signal sqlstate '45000' set message_text = msg;
END IF;
END
//
DELIMITER;
Thank You!
BTW: I'm using mysql version : 5.6.24 .. just in case
I am having an error and I can't make sense of it. Here is the code for my trigger:
CREATE TRIGGER before_insert_test
BEFORE INSERT ON player_totals FOR EACH ROW
BEGIN
IF NEW.Player = 'Player' THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'basketball-reference duplicate header';
END IF;
END;
I am getting red errors marks in MySQL workbench source code editor for 3 lines. For the line that begins SIGNAL SQLSTATE ..., It says:
Syntax Error: missing 'semicolon'
For the line that reads END IF;, the error says:
Syntax error: END (end) is not valid input as this position.
For the line that reads END;, the error says:
Extraneous input found - expected end of statement
Just not sure how to fix these errors, from what I've seen this looks like the correct syntax...
Try this one, with $$ after END
DELIMITER $$
CREATE TRIGGER before_insert_test
BEFORE INSERT ON player_totals
FOR EACH ROW
BEGIN
IF NEW.Player = 'Player' THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'basketball-reference duplicate header';
END IF;
END; $$
DELIMITER ;