CREATE TRIGGER tree_ai_projects_1
AFTER INSERT ON
    projects
FOR EACH ROW 
BEGIN

    

    INSERT INTO
        projects_tree (
            parent,
            child,
            depth
        )
    VALUES (
        NEW.id,
        NEW.id,
        0
    );

    

    INSERT INTO
        projects_tree (
            parent,
            child,
            depth
        )
    SELECT
        x.parent,
        NEW.id,
        x.depth + 1
    FROM
        projects_tree x
    WHERE
        x.child = NEW.parent_id
    ;

END;