【详解】服务器保持与MySQL的连接

[mysqld]
wait_timeout = 28800
interactive_timeout = 28800
max_connections = 500

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC
    username: root
    password: root
    driver-class-name: com.mysql.cj.jdbc.Driver
    hikari:
      connection-timeout: 30000
      idle-timeout: 600000
      max-lifetime: 1800000
      maximum-pool-size: 10

pip install pymysql

import pymysql
from pymysql.cursors import DictCursor
import time

# 数据库配置信息
db_config = {
    'host': '127.0.0.1',
    'port': 3306,
    'user': 'root',
    'password': 'your_password',
    'database': 'test_db',
    'charset': 'utf8mb4'
}

def create_connection():
    """创建数据库连接"""
    return pymysql.connect(**db_config)

def execute_query(conn, query):
    """执行SQL查询并返回结果"""
    try:
        with conn.cursor(DictCursor) as cursor:
            cursor.execute(query)
            result = cursor.fetchall()
            return result
    except Exception as e:
        print(f"Error executing query: {e}")
        return None

def main():
    # 创建数据库连接
    conn = create_connection()
    if not conn:
        print("Failed to connect to the database")
        return

    try:
        while True:
            # 执行一个简单的查询
            query = "SELECT * FROM users LIMIT 5"
            results = execute_query(conn, query)
            if results:
                for row in results:
                    print(row)
            else:
                print("No data returned from the query")

            # 模拟定期查询，每5秒一次
            time.sleep(5)
    finally:
        # 确保最后关闭连接
        conn.close()

if __name__ == "__main__":
    main()

pip install pymysql
pip install DBUtils

from DBUtils.PooledDB import PooledDB
import pymysql

# 数据库配置信息
db_config = {
    'host': '127.0.0.1',
    'port': 3306,
    'user': 'your_username',
    'password': 'your_password',
    'database': 'your_database',
    'charset': 'utf8mb4'
}

# 创建连接池
pool = PooledDB(
    creator=pymysql,  # 使用链接数据库的模块
    maxconnections=6,  # 连接池允许的最大连接数，0和None表示不限制连接数
    mincached=2,  # 初始化时，链接池中至少创建的空闲的链接，0表示不创建
    maxcached=5,  # 链接池中最多闲置的链接，0和None不限制
    maxshared=3,  # 链接池中最多共享的链接数量，0和None表示全部共享。PS: 无用，因为pymysql和MySQLdb等模块的 threadsafety都为1，所有值无论设置为多少，maxcached永远为0，所以永远是所有链接都共享。
    blocking=True,  # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
    maxusage=None,  # 一个链接最多被重复使用的次数，None表示无限制
    setsession=[],  # 开始会话前执行的命令列表。如：["set datestyle to ...", "set time zone ..."]
    ping=0,  # ping MySQL服务端，检查是否服务可用。如：0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is created, 4 = when a query is executed, 7 = always
    **db_config  # 数据库连接参数
)

def execute_query(query, params=()):
    # 从连接池中获取一个连接
    conn = pool.connection()
    cursor = conn.cursor()
    
    try:
        # 执行查询
        cursor.execute(query, params)
        result = cursor.fetchall()
        return result
    except Exception as e:
        print(f"An error occurred: {e}")
        return None
    finally:
        # 关闭游标和连接
        cursor.close()
        conn.close()

# 示例查询
query = "SELECT * FROM users WHERE age > %s"
params = (18,)
results = execute_query(query, params)

for row in results:
    print(row)