一、概述
1.1 Python操作MySQL的常用库
Python操作MySQL数据库有多种选择，各有特点：
| 库名 | 特点 | 适用场景 |
|---|---|---|
| PyMySQL | 纯Python实现，安装简单，兼容性好 | 通用场景，无需编译 |
| mysql-connector-python | MySQL官方驱动，功能完整 | 企业级应用 |
| SQLAlchemy | ORM框架，提供高层次抽象 | 复杂业务，需要对象映射 |
| aiomysql | 异步IO支持 | 高并发异步应用 |
| MySQLdb | C扩展实现，性能高 | 对性能要求高的场景 |
1.2 环境准备
bash
# 安装PyMySQL
pip install pymysql
# 安装mysql-connector-python
pip install mysql-connector-python
# 安装SQLAlchemy（通常配合PyMySQL使用）
pip install sqlalchemy pymysql
# 验证安装
python -c "import pymysql; print(pymysql.__version__)"二、PyMySQL基础使用
2.1 连接数据库
python
import pymysql
# 方式1：使用参数
connection = pymysql.connect(
host='localhost', # 数据库主机地址
port=3306, # 端口号，默认3306
user='root', # 数据库用户名
password='your_password', # 数据库密码
database='school', # 数据库名称
charset='utf8mb4', # 字符集
cursorclass=pymysql.cursors.DictCursor # 返回字典格式结果
)
# 方式2：使用字典参数
config = {
'host': 'localhost',
'port': 3306,
'user': 'root',
'password': 'your_password',
'database': 'school',
'charset': 'utf8mb4',
'cursorclass': pymysql.cursors.DictCursor
}
connection = pymysql.connect(**config)
# 关闭连接
connection.close()2.2 使用上下文管理器
python
import pymysql
# 推荐：使用with语句自动管理连接
with pymysql.connect(
host='localhost',
user='root',
password='your_password',
database='school',
charset='utf8mb4'
) as connection:
with connection.cursor() as cursor:
cursor.execute("SELECT VERSION()")
version = cursor.fetchone()
print(f"MySQL版本: {version[0]}")2.3 连接池实现
python
import pymysql
from contextlib import contextmanager
from queue import Queue
import threading
class MySQLConnectionPool:
"""简单的MySQL连接池实现"""
def __init__(self, max_connections=10, **db_config):
self.max_connections = max_connections
self.db_config = db_config
self._pool = Queue(maxsize=max_connections)
self._lock = threading.Lock()
# 初始化连接池
for _ in range(max_connections):
self._pool.put(self._create_connection())
def _create_connection(self):
"""创建新连接"""
return pymysql.connect(**self.db_config)
@contextmanager
def get_connection(self):
"""获取连接（上下文管理器）"""
conn = self._pool.get()
try:
yield conn
finally:
self._pool.put(conn)
def close_all(self):
"""关闭所有连接"""
while not self._pool.empty():
conn = self._pool.get()
conn.close()
# 使用示例
pool = MySQLConnectionPool(
max_connections=5,
host='localhost',
user='root',
password='your_password',
database='school',
charset='utf8mb4'
)
with pool.get_connection() as conn:
with conn.cursor() as cursor:
cursor.execute("SELECT * FROM students LIMIT 10")
results = cursor.fetchall()
print(results)
# 程序结束时关闭连接池
pool.close_all()三、数据操作（CRUD）
3.1 创建数据库和表
python
import pymysql
def init_database():
"""初始化数据库和表"""
connection = pymysql.connect(
host='localhost',
user='root',
password='your_password',
charset='utf8mb4'
)
try:
with connection.cursor() as cursor:
# 创建数据库
cursor.execute("CREATE DATABASE IF NOT EXISTS school")
cursor.execute("USE school")
# 创建学生表
cursor.execute("""
CREATE TABLE IF NOT EXISTS students (
id INT AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(50) NOT NULL,
age TINYINT UNSIGNED,
gender ENUM('男', '女', '保密') DEFAULT '保密',
score DECIMAL(5,2) DEFAULT 0.00,
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
)
""")
# 创建班级表
cursor.execute("""
CREATE TABLE IF NOT EXISTS classes (
id INT AUTO_INCREMENT PRIMARY KEY,
class_name VARCHAR(50) NOT NULL,
grade VARCHAR(20)
)
""")
connection.commit()
print("数据库和表创建成功")
finally:
connection.close()
if __name__ == "__main__":
init_database()3.2 插入数据（INSERT）
python
import pymysql
def insert_single_record():
"""插入单条记录"""
connection = pymysql.connect(
host='localhost',
user='root',
password='your_password',
database='school',
charset='utf8mb4'
)
try:
with connection.cursor() as cursor:
# 方式1：直接拼接（不推荐，有SQL注入风险）
# cursor.execute(f"INSERT INTO students (name, age) VALUES ('{name}', {age})")
# 方式2：参数化查询（推荐，防止SQL注入）
sql = "INSERT INTO students (name, age, gender, score) VALUES (%s, %s, %s, %s)"
cursor.execute(sql, ('张三', 18, '男', 85.5))
connection.commit()
print(f"插入成功，影响行数: {cursor.rowcount}")
print(f"自增ID: {cursor.lastrowid}")
finally:
connection.close()
def insert_multiple_records():
"""批量插入多条记录"""
connection = pymysql.connect(
host='localhost',
user='root',
password='your_password',
database='school',
charset='utf8mb4'
)
try:
with connection.cursor() as cursor:
sql = "INSERT INTO students (name, age, gender, score) VALUES (%s, %s, %s, %s)"
data = [
('李四', 19, '男', 92.0),
('王芳', 18, '女', 88.5),
('赵强', 20, '男', 76.0),
('孙丽', 19, '女', 95.5)
]
# executemany用于批量插入
cursor.executemany(sql, data)
connection.commit()
print(f"批量插入成功，影响行数: {cursor.rowcount}")
finally:
connection.close()
def insert_or_update():
"""插入或更新（ON DUPLICATE KEY UPDATE）"""
connection = pymysql.connect(
host='localhost',
user='root',
password='your_password',
database='school',
charset='utf8mb4'
)
try:
with connection.cursor() as cursor:
# 假设id=1的记录已存在
sql = """
INSERT INTO students (id, name, age, score)
VALUES (%s, %s, %s, %s)
ON DUPLICATE KEY UPDATE
name = VALUES(name),
age = VALUES(age),
score = VALUES(score)
"""
cursor.execute(sql, (1, '张三（更新）', 19, 90.0))
connection.commit()
print(f"插入/更新成功")
finally:
connection.close()
if __name__ == "__main__":
insert_single_record()
insert_multiple_records()