python 连接mysql数据库实现增删改查

连接MySQL数据库可以使用Python中的MySQLdb或者pymysql等库。以下是使用pymysql库实现增删改查的示例代码。

import pymysql

# 连接数据库
conn = pymysql.connect(host='localhost', port=3306, user='root', password='123456', db='test', charset='utf8')

# 插入数据
def insert_data(name, age):
    try:
        cursor = conn.cursor()
        sql = "INSERT INTO students(name, age) VALUES (%s, %s)"
        cursor.execute(sql, (name, age))
        conn.commit()
        print('插入成功')
    except Exception as e:
        conn.rollback()
        print('插入失败', e)
    finally:
        cursor.close()

# 删除数据
def delete_data(id):
    try:
        cursor = conn.cursor()
        sql = "DELETE FROM students WHERE id = %s"
        cursor.execute(sql, id)
        conn.commit()
        print('删除成功')
    except Exception as e:
        conn.rollback()
        print('删除失败', e)
    finally:
        cursor.close()

# 更新数据
def update_data(id, age):
    try:
        cursor = conn.cursor()
        sql = "UPDATE students SET age = %s WHERE id = %s"
        cursor.execute(sql, (age, id))
        conn.commit()
        print('更新成功')
    except Exception as e:
        conn.rollback()
        print('更新失败', e)
    finally:
        cursor.close()

# 查询数据
def query_data(name):
    try:
        cursor = conn.cursor()
        sql = "SELECT * FROM students WHERE name = %s"
        cursor.execute(sql, name)
        results = cursor.fetchall()
        for row in results:
            id = row[0]
            name = row[1]
            age = row[2]
            print(f'id={id}, name={name}, age={age}')
    except Exception as e:
        print('查询失败', e)
    finally:
        cursor.close()

if __name__ == '__main__':
    insert_data('张三', 20)
    delete_data(1)
    update_data(2, 22)
    query_data('张三')

# 关闭连接
conn.close()

以上代码连接到名为test的MySQL数据库中，对students表进行增删改查操作。其中，增加数据使用INSERT语句，删除数据使用DELETE语句，更新数据使用UPDATE语句，查询数据使用SELECT语句。使用try-except-finally结构确保代码执行过程中出现异常时能够及时关闭游标对象，回滚或提交事务，并关闭数据库连接。