I am a new to queries in dbms, so If someone could figure out what should be done here. Also, I am using Mysql.
code:
-> create trigger age_trigger before insert or update of age on employee
-> for each row
-> when( new.age <25)
-> begin
-> select 'Age can not be less than 25'
-> end;
error:
ERROR 1064 (42000): You have an error in your SQL syntax; check the
manual that corresponds to your MySQL server version for the right
syntax to use near 'or update of age on employee for each row when(
new.age <25) begin select 'Age c' at line 1
You can't just come up with your own syntax :)
Have a look at the manual: CREATE TRIGGER Syntax
You can't specify multiple trigger_events. You need separate insert and update triggers. And this of age also has no business there.
All in all, what you're trying to do there can be done in MySQL (google for SIGNAL, if you insist), but best practice is, that this sort of logic is placed in the application layer. Don't put such logic in the database.
Below can be one of the option to implement BEFORE INSERT to obtain your desired result.
CREATE TRIGGER age_trigger
BEFORE INSERT ON table1
FOR EACH ROW
BEGIN
IF NEW.age < 25
THEN SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'Age can not be less than 25';
END IF;
END;
Similar syntax can be used for before update trigger.
DEMO
Related
I want to create a trigger that rejects the insert of an underage employee, by underage I mean that his year of birth is 2004 or more.
I wrote the following code, it runs without errors but then it doesn't let me insert any employee because it says :
ERROR: Unknown column 'BIRTHDATE' IN 'field list'
When I drop the trigger everything works fine.
DELIMITER $$
CREATE TRIGGER REJECT_EMP
BEFORE INSERT ON EMPLOYEE
FOR EACH ROW
BEGIN
IF YEAR(BIRTHDATE) > 2003 THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'An error occurred';
END IF;
END$$
DELIMITER ;
You should be testing NEW.BIRTHDATE
'Within the trigger body, the OLD and NEW keywords enable you to access columns in the rows affected by a trigger.' https://dev.mysql.com/doc/refman/8.0/en/trigger-syntax.html
If you are running MySQL 8.0, I would recommend a check constraint rather than trigger logic.
alter table employee
add constraint chk_birthdate
check(year(birthdate) > 2003)
;
This enforces the same check that the trigger does, but the syntax is much shorter, and the logic is bundled directly in the definition of the table (so it is somehow easier to maintain). When an attempt is made to insert an offending row, you get the following error message:
Check constraint 'chk_birthdate' is violated.
I have to advice 2 changes in your trigger:
fist as #P.Salmon answered you should to use NEW.BIRTHDATE parameter
second use age instead birth-year in comparison
DELIMITER $$
CREATE TRIGGER REJECT_EMP
BEFORE INSERT ON EMPLOYEE
FOR EACH ROW
BEGIN
IF TIMESTAMPDIFF(YEAR, NEW.BIRTHDATE, NOW()) < 17 THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'An error occurred';
END IF;
END$$
DELIMITER ;
In general, the right way to check year() is on a day-by-day basis. So the logic that you want is:
BEGIN
IF BIRTHDATE > CURDATE() - INTERVAL 16 YEAR THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'An error occurred';
END IF;
END$$
This actually checks the date of birth. So someone can become an employee on their birthday.
I am not sure "16" is the right value, but your question doesn't explain it. It makes sense given the logic you have presented and that the year when you asked the question is 2020.
I'm trying to create a trigger whereby an insertion on one table updates another. This is my SQL Query:
CREATE TRIGGER makePayment AFTER INSERT ON Payments FOR EACH ROW
BEGIN
UPDATE Invoice
SET InvoiceClientPaid = SUM(InvoiceClientPaid + NEW.PaymentAmt)
WHERE InvoiceID = NEW.PaymentInvoiceID;
END;
No matter what I do I get the following error:
Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 6
I don't think it's related to the SUM, because trying a basic = 1 on the SET command gives me the exact error. There is no '' at line 6 which is very confusing?
If you're entering this query directly into MySQL you will need to change the delimiter prior to the query using (e.g.) DELIMITER //, otherwise it thinks the query ends at the ; at the end of your UPDATE statement. MySQL then sees an END with nothing before it and complains about the nothing (''). So try this:
DELIMITER //
CREATE TRIGGER makePayment AFTER INSERT ON Payments FOR EACH ROW
BEGIN
UPDATE Invoice
SET InvoiceClientPaid = SUM(InvoiceClientPaid + NEW.PaymentAmt)
WHERE InvoiceID = NEW.PaymentInvoiceID;
END; //
DELIMITER ;
I just want to create a trigger for my phpmyadmin. Basically the intended function is whenever I update a credit column of my finance table, the balance column will be automatically updated for each row.
My program is:
CREATE TRIGGER UPDATE_BALANCE AFTER UPDATE financeofstudents
FOR EACH ROW
BEGIN
IF financeofstudents.credit > 0
AND
financeofstudents.credit <= financeofstudents.debit
THEN
UPDATE financeofstudents SET financeofstudents.balance = financeofstudents.debit- financeofstudents.credit;
END IF;
END
but it gives me this error:
Error
SQL query:
CREATE TRIGGER UPDATE_BALANCE AFTER UPDATE financeofstudents
FOR EACH ROW
BEGIN
IF financeofstudents.credit > 0
AND
financeofstudents.credit <= financeofstudents.debit
THEN
UPDATE financeofstudents SET financeofstudents.balance = financeofstudents.debit-financeofstudents.credit
MySQL said: Documentation
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'financeofstudents
FOR EACH ROW
BEGIN
IF financeofstudents.credit > 0
AND
f' at line 1
I don't know where is the problem. Expert guys, please help me.
The error message is a useful hint here. It says .. for the right syntax to use near 'some text from your query starting with the first thing it didn't understand'.
In your case, you need the word ON before the name of the table.
CREATE TRIGGER update_balance
AFTER UPDATE
ON financeofstudents
FOR EACH ROW
If you observed that MySQL error messages are hard to interpret, you would be correct.
How can I create a trigger using the below code to stop overlapping dates in my booking table? Currently it's not working and i'm getting the following error.
1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IF EXISTS
(SELECT *
FROM booking_requests
WHERE DateOfArrival <= NEW.' at line 3
CREATE TRIGGER date_overlap
BEFORE INSERT ON hotel_booking
IF EXISTS
(
SELECT *
FROM booking_requests
WHERE DateOfArrival <= NEW.DateOfDeparture
AND DateOfDeparture >= NEW.DateOfArrival
AND (RoomNumber != NEW.RoomNumber)
)
THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'overlapping date entries are not supported.';
END IF;
IF EXISTS (
... # this part looks about right, except for the last line, which
# you only need in the update trigger and should simply say:
AND (id != NEW.id)
) THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'overlapping date entries are not supported.';
END IF;
Valid for MySQL Server 5.5 and later.
This needs to be in both a BEFORE INSERT and a BEFORE UPDATE trigger.
Multi-column indexes on both (date_start,date_end) and (date_end,date_start) will allow the optimizer the best chance of identifying conflicting rows quickly, since it can search via range on either column and scan the values in other from the index directly, using it as a covering index.
It's my first time that I try to use trigger on mysql (and generally I don't use mysql so much).
The version of mysql that I'm using is 5.5.40 and the code I'm using to create the trigger is:
CREATE TRIGGER updateTrigger
AFTER UPDATE ON tab1
FOR EACH ROW
BEGIN
UPDATE tab2
SET field1 = NEW.field1
WHERE field2 = NEW.field2;
END;
Where field1 and field2 are two fields in both tables (tab1 and tab2) both archer(120).
When I try to execute this code I receive an error:
#1064 - You have an error in your SQL syntax;
check the manual that corresponds to your MySQL server version
for the right syntax to use near '' at line 7
(line 7 is near "WHEN" keyword).
I checked several answer on stack overflow and other web sites, I tried with and without delimiters, and I still not able to create a trigger.
What's my syntax error?
Is there some way to have some more accurate mysql debugging? Actually mysql answer (like I just posted) is just "there is an error (1064)" but it doesn't let me know what is wrong.
you have to change the delimiter to use it in your sql statement :
DELIMITER //
CREATE TRIGGER updateTrigger
AFTER UPDATE ON tab1
FOR EACH ROW
BEGIN
UPDATE tab2
SET field1 = NEW.field1
WHERE field2 = NEW.field2;
END//
DELIMITER ;