MySQL trigger doesn't response, WHY?

Question

I am new to SQL and I don't know where to get help. I faced a problem while using the trigger, but it doesn't response. This is my code here:

DELIMITER $$
CREATE TRIGGER payments_after_insert
    AFTER INSERT ON payments

    FOR EACH ROW
BEGIN 
    UPDATE invoices 
    SET payment_total = payment_total + NEW.amount
    WHERE invoice_id = NEW.invoice_id;
END $$
DELIMITER ; 

Here is the second part:

INSERT INTO payments                                        
VALUES (DEFAULT, 5, 3, '2019-01-01', 10, 1)

I execute the first part, then the second. Strangely the new data has been inserted, but the triggers don't.

Can someone help me? I have been searching for the answers for few days and I don't know how to solve it.

Thank you in advance.

Answer 1

A model:

-- sample structures and data
CREATE TABLE payments (
  id INT AUTO_INCREMENT PRIMARY KEY,
  column1 INT,
  column2 INT,
  somedate DATE,
  amount INT,
  invoice_id INT
);
INSERT INTO payments VALUES 
  (DEFAULT, 5, 3, '2018-01-01', 15, 1),
  (DEFAULT, 5, 3, '2018-02-02', 55, 2);
CREATE TABLE invoices (
  invoice_id INT,
  payment_total INT
);
INSERT INTO invoices VALUES (1,15), (2,55);
SELECT * FROM invoices;
SELECT * FROM payments;

invoice_id	payment_total
1	15
2	55

id	column1	column2	somedate	amount	invoice_id
1	5	3	2018-01-01	15	1
2	5	3	2018-02-02	55	2

-- trigger (copied from the question)
CREATE TRIGGER payments_after_insert
    AFTER INSERT ON payments        
    FOR EACH ROW
BEGIN 
    UPDATE invoices 
    SET payment_total = payment_total + NEW.amount
    WHERE invoice_id = NEW.invoice_id;
END

-- insertion (copied from the question)
INSERT INTO payments                                        
VALUES (DEFAULT, 5, 3, '2019-01-01', 10, 1)

-- looking for final data state
SELECT * FROM invoices;
SELECT * FROM payments;

invoice_id	payment_total
1	25
2	55

id	column1	column2	somedate	amount	invoice_id
1	5	3	2018-01-01	15	1
2	5	3	2018-02-02	55	2
3	5	3	2019-01-01	10	1

fiddle