DROP TABLE items;
drop trigger TREE_IN;

CREATE TABLE items (
  id INT PRIMARY KEY,
  parent_id INTEGER,
  title VARCHAR(256),
  status VARCHAR(32),
  kind VARCHAR(32),
  string TEXT
);

DELIMITER |
CREATE TRIGGER TREE_IN BEFORE INSERT ON items
FOR EACH ROW
BEGIN
    CASE
    WHEN parent_id is null then (SET NEW.string = 'caca';)
    ELSE (SET NEW.string = 'caca2';)
    END;
END;
|
DELIMITER ;


INSERT INTO items (id, parent_id, title, status, kind) VALUES (1, NULL, 'Homepage', 'Published', 'Homepage');