从数据库中使用cron表达式执行调度方法

import sqlite3
import time
from croniter import croniter
from datetime import datetime

# 创建数据库连接
conn = sqlite3.connect('example.db')
cursor = conn.cursor()

# 创建表
cursor.execute('''CREATE TABLE IF NOT EXISTS tasks (
                    id INTEGER PRIMARY KEY,
                    task TEXT NOT NULL,
                    cron_expression TEXT NOT NULL
                )''')

# 插入任务
cursor.execute("INSERT INTO tasks (task, cron_expression) VALUES (?, ?)", ("backup_database", "0 0 * * *"))

# 提交事务
conn.commit()

# 定时任务调度
def run_scheduled_tasks():
    while True:
        cursor.execute("SELECT task, cron_expression FROM tasks")
        tasks = cursor.fetchall()
        for task, cron_expr in tasks:
            cron = croniter(cron_expr, datetime.now())
            next_run = cron.get_next(datetime)
            if next_run <= datetime.now():
                print(f"Running task: {task}")
                # 执行任务逻辑
                # ...
        time.sleep(60)  # 每分钟检查一次

if __name__ == "__main__":
    run_scheduled_tasks()