MySQL 8.0

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CREATE TABLE table1 (
  id INT,
  dep INT,
  cash INT,
  advance INT,
  ratio DECIMAL(18,2)
);
INSERT INTO table1 VALUES
  (1, 100, 100, 200, 0),
  (2, 200, 300, 500, 0);
SELECT * FROM table1;


id
dep
cash
advance
ratio


1
100
100
200
0.00

2
200
300
500
0.00


CREATE TRIGGER upd_ratio BEFORE UPDATE ON table1
FOR EACH ROW 
BEGIN
    SET NEW.ratio = NEW.advance / NEW.dep;
END
UPDATE table1 SET dep = 200 WHERE id = 1;
SELECT * FROM table1;


id
dep
cash
advance
ratio


1
200
100
200
1.00

2
200
300
500
0.00