mysql 多字段自增长

DELIMITER //
CREATE TRIGGER before_order_insert
BEFORE INSERT ON orders
FOR EACH ROW
BEGIN
    DECLARE new_order_id INT;
    SET new_order_id = (SELECT IFNULL(MAX(order_id), 0) + 1 FROM orders);
    SET NEW.order_id = new_order_id;
    SET NEW.sub_order_id = (SELECT IFNULL(MAX(sub_order_id), 0) + 1 FROM orders WHERE order_id = new_order_id);
END;
//
DELIMITER ;

import time
import random

class SnowflakeIDGenerator:
    def __init__(self, machine_id):
        self.machine_id = machine_id
        self.sequence = 0
        self.last_timestamp = -1

    def generate_id(self):
        timestamp = int(time.time() * 1000)
        if timestamp < self.last_timestamp:
            raise Exception("Clock moved backwards. Refusing to generate id for %d milliseconds" % (self.last_timestamp - timestamp))
        if timestamp == self.last_timestamp:
            self.sequence = (self.sequence + 1) & 4095
            if self.sequence == 0:
                timestamp = self.til_next_millis(self.last_timestamp)
        else:
            self.sequence = random.randint(0, 4095)
        self.last_timestamp = timestamp
        return ((timestamp - 1288834974657) << 22) | (self.machine_id << 12) | self.sequence

    def til_next_millis(self, last_timestamp):
        timestamp = int(time.time() * 1000)
        while timestamp <= last_timestamp:
            timestamp = int(time.time() * 1000)
        return timestamp

# 示例使用
generator = SnowflakeIDGenerator(machine_id=1)
new_id = generator.generate_id()
print(new_id)