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CREATE TABLE articles (id INT, image VARCHAR(255));
CREATE TRIGGER tr_name
BEFORE INSERT
ON articles
FOR EACH ROW
SET NEW.image = CONCAT('catalog/blog-image/', COALESCE((SELECT 1 + MAX(SUBSTRING_INDEX(image, '/', -1)) FROM articles), 1), '.jpg');
INSERT INTO articles (id) VALUES (1);
SELECT * FROM articles;
| id | image |
|---|---|
| 1 | catalog/blog-image/1.jpg |
INSERT INTO articles (id) VALUES (2);
SELECT * FROM articles;
| id | image |
|---|---|
| 1 | catalog/blog-image/1.jpg |
| 2 | catalog/blog-image/2.jpg |
INSERT INTO articles (id) VALUES (3);
SELECT * FROM articles;
| id | image |
|---|---|
| 1 | catalog/blog-image/1.jpg |
| 2 | catalog/blog-image/2.jpg |
| 3 | catalog/blog-image/3.jpg |