以下是 Python 连接 MySQL 数据库的完整步骤，包含环境准备、连接建立、数据操作、错误处理和性能优化等内容：
一、环境准备
- 安装 MySQL 服务器
Windows/macOS：下载安装包 MySQL Installer
Linux：
bash
var code = "318e5627-2db9-4012-a210-8aed2d29ce19"
Ubuntu/Debian
sudo apt-get install mysql-server
CentOS/RHEL
sudo yum install mysql-server
- 启动 MySQL 服务
bash
Linux/macOS
sudo service mysql start
Windows
net start mysql
- 创建测试数据库和用户
sql
-- 登录MySQL
mysql -u root -p
-- 创建数据库
CREATE DATABASE testdb;
-- 创建用户并授权
CREATE USER 'testuser'@'localhost' IDENTIFIED BY 'testpassword';
GRANT ALL PRIVILEGES ON testdb.* TO 'testuser'@'localhost';
FLUSH PRIVILEGES;
- 安装 Python 驱动
bash
pip install mysql-connector-python
二、建立数据库连接
- 基本连接示例
python
import mysql.connector
from mysql.connector import Error
try:
connection = mysql.connector.connect(
host='localhost',
user='testuser',
password='testpassword',
database='testdb',
port=3306 # 默认端口
)
if connection.is_connected():
db_info = connection.get_server_info()
print(f"连接成功，MySQL服务器版本: {db_info}")
cursor = connection.cursor()
cursor.execute("SELECT DATABASE();")
database = cursor.fetchone()
print(f"当前数据库: {database}")except Error as e:
print(f"连接错误: {e}")
finally:
if connection.is_connected():
cursor.close()
connection.close()
print("数据库连接已关闭")
- 连接参数详解
python
connection = mysql.connector.connect(
host='localhost', # 主机地址
user='testuser', # 用户名
password='testpassword', # 密码
database='testdb', # 数据库名
port=3306, # 端口号
charset='utf8mb4', # 字符集
autocommit=True, # 自动提交事务
connection_timeout=10 # 连接超时时间（秒）
)
三、执行 SQL 操作
-
创建表
python
try:
connection = mysql.connector.connect(...)
cursor = connection.cursor()
create_table_query = """
CREATE TABLE IF NOT EXISTS employees (
id INT AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(255) NOT NULL,
department VARCHAR(255) NOT NULL,
salary DECIMAL(10, 2) NOT NULL,
hire_date DATE NOT NULL
)
"""
cursor.execute(create_table_query)
print("表创建成功")
except Error as e:
print(f"表创建失败: {e}")
- 插入数据
python
try:
connection = mysql.connector.connect(...)
cursor = connection.cursor()
# 单条插入
insert_query = """
INSERT INTO employees (name, department, salary, hire_date)
VALUES (%s, %s, %s, %s)
"""
employee_data = ("John Doe", "IT", 5000.00, "2023-01-15")
cursor.execute(insert_query, employee_data)
# 批量插入
employees_data = [
("Jane Smith", "HR", 6000.00, "2023-02-20"),
("Robert Johnson", "Finance", 5500.00, "2023-03-10")
]
cursor.executemany(insert_query, employees_data)
connection.commit() # 提交事务
print(f"插入成功，影响行数: {cursor.rowcount}")except Error as e:
print(f"插入失败: {e}")
connection.rollback() # 回滚事务
- 查询数据
python
try:
connection = mysql.connector.connect(...)
cursor = connection.cursor()
# 查询所有记录
select_query = "SELECT * FROM employees"
cursor.execute(select_query)
records = cursor.fetchall()
print(f"共查询到 {cursor.rowcount} 条记录")
for row in records:
print(f"ID: {row[0]}, 姓名: {row[1]}, 部门: {row[2]}, 薪水: {row[3]}")
# 参数化查询
select_salary_query = "SELECT * FROM employees WHERE salary > %s"
cursor.execute(select_salary_query, (5000,))
high_salary_employees = cursor.fetchall()
print(f"高薪员工: {len(high_salary_employees)} 人")except Error as e:
print(f"查询失败: {e}")
- 更新数据
python
try:
connection = mysql.connector.connect(...)
cursor = connection.cursor()
update_query = "UPDATE employees SET salary = salary * 1.1 WHERE department = %s"
cursor.execute(update_query, ("IT",))
connection.commit()
print(f"更新成功，影响行数: {cursor.rowcount}")except Error as e:
print(f"更新失败: {e}")
connection.rollback()
- 删除数据
python
try:
connection = mysql.connector.connect(...)
cursor = connection.cursor()
delete_query = "DELETE FROM employees WHERE hire_date < %s"
cursor.execute(delete_query, ("2023-02-01",))
connection.commit()
print(f"删除成功，影响行数: {cursor.rowcount}")except Error as e:
print(f"删除失败: {e}")
connection.rollback()
四、高级操作
- 使用字典游标
python
cursor = connection.cursor(dictionary=True)
cursor.execute("SELECT * FROM employees")
records = cursor.fetchall()
for row in records:
print(f"姓名: {row['name']}, 部门: {row['department']}")
- 事务处理
python
try:
connection = mysql.connector.connect(...)
connection.autocommit = False # 关闭自动提交
cursor = connection.cursor()
# 执行多个操作
cursor.execute("INSERT INTO employees (...) VALUES (...)")
cursor.execute("UPDATE departments SET budget = budget - 10000")
connection.commit() # 提交事务
print("事务执行成功")except Error as e:
print(f"事务失败: {e}")
connection.rollback() # 回滚事务
- 连接池
python
from mysql.connector import pooling
创建连接池
connection_pool = pooling.MySQLConnectionPool(
pool_name="mypool",
pool_size=5,
host='localhost',
user='testuser',
password='testpassword',
database='testdb'
)
从连接池获取连接
connection = connection_pool.get_connection()
cursor = connection.cursor()
cursor.execute("SELECT * FROM employees")
五、错误处理与最佳实践
-
常见错误类型
python
try:
connection = mysql.connector.connect(...)数据库操作
except mysql.connector.Error as e:
if e.errno == 1045: # 访问拒绝
print("用户名或密码错误")
elif e.errno == 1049: # 数据库不存在
print("数据库不存在")
elif e.errno == 2003: # 无法连接
print("无法连接到MySQL服务器")
else:
print(f"未知错误: {e}")
- 资源管理
python
使用上下文管理器自动关闭连接和游标
with mysql.connector.connect(...) as connection:
with connection.cursor() as cursor:
cursor.execute("SELECT * FROM employees")
records = cursor.fetchall()
- 性能优化
python
批量插入优化
data = [(f"User{i}", "Dept", 5000) for i in range(1000)]
cursor.executemany("INSERT INTO users VALUES (%s, %s, %s)", data)
使用预编译语句
stmt = connection.prepare("INSERT INTO users VALUES (?, ?, ?)")
cursor.execute(stmt, ("User1", "Dept", 5000))
六、安全注意事项
避免 SQL 注入：
python
错误做法（不安全）
query = f"SELECT * FROM users WHERE name = '{name}'"
正确做法（使用参数化查询）
query = "SELECT * FROM users WHERE name = %s"
cursor.execute(query, (name,))
密码管理：
python
不要硬编码密码
推荐使用环境变量或配置文件
import os
password = os.environ.get('MYSQL_PASSWORD')
权限最小化：
sql
-- 为应用创建具有最小权限的用户
GRANT SELECT, INSERT, UPDATE ON testdb.* TO 'appuser'@'localhost';