mysql删除30天之前的数据库

DELIMITER $$

CREATE PROCEDURE delete_old_databases()
BEGIN
    DECLARE db_name VARCHAR(255);
    DECLARE done INT DEFAULT FALSE;
    DECLARE cur CURSOR FOR SELECT schema_name FROM information_schema.schemata WHERE schema_name NOT IN ('information_schema', 'mysql', 'performance_schema');
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO db_name;

        IF done THEN
            LEAVE read_loop;
        END IF;

        SET @sql := CONCAT('SELECT DATEDIFF(NOW(), MAX(create_time)) INTO @diff FROM ', db_name, '.tbl_name');
        PREPARE stmt FROM @sql;
        EXECUTE stmt;
        DEALLOCATE PREPARE stmt;

        IF @diff > 30 THEN
            SET @sql := CONCAT('DROP DATABASE ', db_name);
            PREPARE stmt FROM @sql;
            EXECUTE stmt;
            DEALLOCATE PREPARE stmt;
        END IF;
    END LOOP;

    CLOSE cur;
END$$

DELIMITER ;

CREATE EVENT delete_old_databases_event
    ON SCHEDULE EVERY 1 DAY
    STARTS '2022-01-01 00:00:00'
    DO
        CALL delete_old_databases();

CALL delete_old_databases();