Python使用PyMySQL操作MySQL完整指南
1. 安装依赖
bash
pip install pymysql2. 基础配置和数据库操作
2.1 基础配置类
python
import pymysql
from typing import List, Dict, Optional
from datetime import datetime
class MySQLDB:
def __init__(self):
self.conn = None
self.cursor = None
def connect(self):
"""连接数据库"""
try:
self.conn = pymysql.connect(
host='localhost',
port=3306,
user='root',
password='123456',
charset='utf8mb4',
cursorclass=pymysql.cursors.DictCursor # 返回字典格式
)
self.cursor = self.conn.cursor()
except Exception as e:
print(f"连接数据库失败：{e}")
raise e
def close(self):
"""关闭数据库连接"""
if self.cursor:
self.cursor.close()
if self.conn:
self.conn.close()2.2 数据库和表操作
python
def create_database(self):
"""创建数据库"""
try:
sql = "CREATE DATABASE IF NOT EXISTS test DEFAULT CHARACTER SET utf8mb4"
self.cursor.execute(sql)
self.conn.select_db('test') # 选择数据库
except Exception as e:
print(f"创建数据库失败：{e}")
raise e
def drop_database(self):
"""删除数据库"""
try:
sql = "DROP DATABASE IF EXISTS test"
self.cursor.execute(sql)
except Exception as e:
print(f"删除数据库失败：{e}")
raise e
def create_table(self):
"""创建用户表"""
try:
sql = """
CREATE TABLE IF NOT EXISTS users (
id BIGINT PRIMARY KEY AUTO_INCREMENT COMMENT '自增主键',
username VARCHAR(50) NOT NULL UNIQUE COMMENT '用户名',
password VARCHAR(100) NOT NULL COMMENT '密码',
age INT COMMENT '年龄',
create_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
INDEX idx_username (username)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='用户表';
"""
self.cursor.execute(sql)
self.conn.commit()
except Exception as e:
self.conn.rollback()
print(f"创建表失败：{e}")
raise e3. CRUD操作
3.1 插入操作
python
def insert_user(self, username: str, password: str, age: int) -> int:
"""插入单个用户"""
try:
sql = "INSERT INTO users(username, password, age) VALUES (%s, %s, %s)"
self.cursor.execute(sql, (username, password, age))
self.conn.commit()
return self.cursor.lastrowid # 返回自增ID
except Exception as e:
self.conn.rollback()
print(f"插入用户失败：{e}")
raise e
def batch_insert_users(self, users: List[Dict]):
"""批量插入用户"""
try:
sql = "INSERT INTO users(username, password, age) VALUES (%s, %s, %s)"
values = [(user['username'], user['password'], user['age']) for user in users]
self.cursor.executemany(sql, values)
self.conn.commit()
except Exception as e:
self.conn.rollback()
print(f"批量插入用户失败：{e}")
raise e3.2 查询操作
python
def get_user_by_id(self, user_id: int) -> Optional[Dict]:
"""根据ID查询用户"""
try:
sql = "SELECT * FROM users WHERE id = %s"
self.cursor.execute(sql, (user_id,))
return self.cursor.fetchone()
except Exception as e:
print(f"查询用户失败：{e}")
raise e
def get_users_by_age(self, min_age: int) -> List[Dict]:
"""查询大于指定年龄的用户"""
try:
sql = "SELECT * FROM users WHERE age > %s"
self.cursor.execute(sql, (min_age,))
return self.cursor.fetchall()
except Exception as e:
print(f"查询用户失败：{e}")
raise e
def get_users_with_pagination(self, page: int, page_size: int) -> List[Dict]:
"""分页查询用户"""
try:
offset = (page - 1) * page_size
sql = "SELECT * FROM users LIMIT %s OFFSET %s"
self.cursor.execute(sql, (page_size, offset))
return self.cursor.fetchall()
except Exception as e:
print(f"分页查询失败：{e}")
raise e3.3 更新操作
python
def update_user(self, user_id: int, password: str = None, age: int = None) -> bool:
"""更新用户信息"""
try:
updates = []
values = []
if password is not None:
updates.append("password = %s")
values.append(password)
if age is not None:
updates.append("age = %s")
values.append(age)
if not updates:
return False
values.append(user_id)
sql = f"UPDATE users SET {', '.join(updates)} WHERE id = %s"
result = self.cursor.execute(sql, tuple(values))
self.conn.commit()
return result > 0
except Exception as e:
self.conn.rollback()
print(f"更新用户失败：{e}")
raise e3.4 删除操作
python
def delete_user(self, user_id: int) -> bool:
"""删除用户"""
try:
sql = "DELETE FROM users WHERE id = %s"
result = self.cursor.execute(sql, (user_id,))
self.conn.commit()
return result > 0
except Exception as e:
self.conn.rollback()
print(f"删除用户失败：{e}")
raise e4. 使用示例
python
def main():
# 创建数据库实例
db = MySQLDB()
try:
# 连接数据库
db.connect()
# 创建数据库和表
db.create_database()
db.create_table()
# 插入单个用户
user_id = db.insert_user("张三", "123456", 25)
print(f"插入用户ID: {user_id}")
# 批量插入用户
users = [
{"username": "李四", "password": "123456", "age": 26},
{"username": "王五", "password": "123456", "age": 27}
]
db.batch_insert_users(users)
# 查询用户
user = db.get_user_by_id(user_id)
print(f"查询到的用户: {user}")
# 更新用户
db.update_user(user_id, age=30)
# 分页查询
users = db.get_users_with_pagination(1, 10)
print(f"分页查询结果: {users}")
# 删除用户
db.delete_user(user_id)
except Exception as e:
print(f"操作失败：{e}")
finally:
db.close()
if __name__ == "__main__":
main()5. 事务处理示例
python
def transfer_money(self, from_id: int, to_id: int, amount: float):
"""转账操作示例"""
try:
# 开始事务
self.conn.begin()
# 扣除转出账户金额
sql1 = "UPDATE accounts SET balance = balance - %s WHERE id = %s AND balance >= %s"
result1 = self.cursor.execute(sql1, (amount, from_id, amount))
if result1 == 0:
raise Exception("余额不足或账户不存在")
# 增加转入账户金额
sql2 = "UPDATE accounts SET balance = balance + %s WHERE id = %s"
result2 = self.cursor.execute(sql2, (amount, to_id))
if result2 == 0:
raise Exception("转入账户不存在")
# 提交事务
self.conn.commit()
return True
except Exception as e:
# 回滚事务
self.conn.rollback()
print(f"转账失败：{e}")
raise e6. 注意事项
-
连接管理
- 及时关闭数据库连接
- 使用连接池管理连接（可以使用 DBUtils 等库）
- 处理连接超时情况
-
安全性
- 使用参数化查询防止 SQL 注入
- 妥善保管数据库凭证
- 最小权限原则
-
性能优化
- 合理使用索引
- 批量操作代替循环单条操作
- 避免查询无用字段
-
错误处理
- 完善的异常处理机制
- 事务回滚
- 日志记录