mysql生成唯一id

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(255) NOT NULL,
    email VARCHAR(255) NOT NULL UNIQUE
);

CREATE TABLE users (
    id CHAR(36) PRIMARY KEY DEFAULT (UUID()),
    name VARCHAR(255) NOT NULL,
    email VARCHAR(255) NOT NULL UNIQUE
);

import time
import random

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

    def _get_timestamp(self):
        return int(time.time() * 1000)

    def generate_id(self):
        timestamp = self._get_timestamp()
        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._wait_for_next_millis(timestamp)
        else:
            self.sequence = random.randint(0, 4095)
        self.last_timestamp = timestamp
        return ((timestamp - 1288834974657) << 22) | (self.datacenter_id << 17) | (self.worker_id << 12) | self.sequence

    def _wait_for_next_millis(self, last_timestamp):
        timestamp = self._get_timestamp()
        while timestamp <= last_timestamp:
            timestamp = self._get_timestamp()
        return timestamp

# 示例使用
generator = SnowflakeIDGenerator(worker_id=1, datacenter_id=1)
unique_id = generator.generate_id()
print(unique_id)

ALTER TABLE users AUTO_INCREMENT = 1;