How to Trigger in MySql - mysql

Question

I want to create a Trigger in MySql I did it with SQL Server at school in my class, but for my project, my web hoster only give me MySql DataBase and if I want a SQL Server DB I need to buy a VPS and I can't afford it so i'll do with MySql, I read about MySql Trigger and I saw that they are really more hard to do than SQL Server Trigger.
First here is every article I read about trigger in MySql (To be sure to not be placed as a duplica):
https://www.mysqltutorial.org/mysql-triggers.aspx/
https://www.mysqltutorial.org/create-the-first-trigger-in-mysql.aspx/
https://dev.mysql.com/doc/refman/8.0/en/trigger-syntax.html
https://stackoverflow.com/questions/38745441/how-to-write-trigger-with-multiple-condition-in-mysql
https://stackoverflow.com/questions/33775826/how-to-declare-variables-in-trigger-with-mysql
And here is the SQL Server code I made:
CREATE TRIGGER file_verified_if_admin ON tblOpenSource
AFTER INSERT, UPDATE
AS
BEGIN
DECLARE #source_id INT;
DECLARE #verified TEXT;
DECLARE #client_id INT;
DECLARE c_info CURSOR FOR
SELECT source_id, verified, client_id FROM inserted;
OPEN c_info;
FETCH c_info INTO #source_id,#verified,#client_id;
WHILE (##FETCH_STATUS=0)
BEGIN
IF ((SELECT tblClients.grade FROM tblClients JOIN tblOpenSource ON tblOpenSource.client_id = tblClients.client_id;) == 'admin')
BEGIN
UPDATE tblOpenSource SET verified = 'verified' WHERE source_id = #source_id;
END;
END;
CLOSE c_info;
DEALLOCATE c_info;
END;
Here is what I made with MySql and I still have errors, can someone help me ?
CREATE TRIGGER file_verified_if_admin
AFTER INSERT, UPDATE ON tblOpenSource
FOR EACH ROW
BEGIN
DECLARE client_grade text;
SET #client_grade = (SELECT tblClients.grade FROM tblClients JOIN tblOpenSource ON tblClients.client_id = tblOpenSource.client_id);
IF (#client_grade = 'admin')
UPDATE tblOpenSource SET verified = 'verified' WHERE source_id = NEW.source_id;
END;
It says I have an error near my DELCARE, but I don't understand why, because I heard we don't need an "#" in the declaration.
What it is supposed to do, is to look if the file as been publied by an admin and if yes, it should update the verified column and change the text for verified

Answer 1

Mysql desn_'t allow multiple trigger in one goal you have to define then all.
Maysql needs DELIMITERto know where the trigger starts and ends
Last the IÌF CLause`is in mysql different.
This is the correct syntax, you can change it further by using SELECT INTO
UPDATE #Akina poited out,
that your query will not run, you can't change a row that has triggert the Trigger, mysql will not not allow that, so for your insert trigger, has to be change accordingly.
For the UPDATE Trigger goes teh saem.
DELIMITER //
CREATE TRIGGER file_verified_if_admin
BEFORE INSERT ON tblOpenSource
FOR EACH ROW
BEGIN
SET #client_grade = (SELECT tblClients.grade FROM tblClients JOIN tblOpenSource ON tblClients.client_id = tblOpenSource.client_id);
IF (#client_grade = 'admin') then
SET NEW.verified = 'verified';
END IF;
END//
DELIMITER ;