Python MySQL 数据库操作示例：CRUD 和 事务处理

以下是使用 Python 语言编写的可运行代码，实现对 MySQL 数据库的操作，包括创建数据表、增加数据、删除数据、修改数据、查询数据以及事务处理的功能：

import pymysql

# 连接数据库
conn = pymysql.connect(host='localhost', user='root', password='password', database='testdb')
cursor = conn.cursor()

# 创建数据表
create_table_query = '''
CREATE TABLE IF NOT EXISTS trade (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(255),
    price FLOAT,
    quantity INT
)
'''
cursor.execute(create_table_query)
conn.commit()

# 增加数据
def add_trade(name, price, quantity):
    add_trade_query = '''
    INSERT INTO trade (name, price, quantity) VALUES (%s, %s, %s)
    '''
    cursor.execute(add_trade_query, (name, price, quantity))
    conn.commit()

# 删除数据
def delete_trade(trade_id):
    delete_trade_query = '''
    DELETE FROM trade WHERE id = %s
    '''
    cursor.execute(delete_trade_query, (trade_id,))
    conn.commit()

# 修改数据
def update_trade(trade_id, name, price, quantity):
    update_trade_query = '''
    UPDATE trade SET name = %s, price = %s, quantity = %s WHERE id = %s
    '''
    cursor.execute(update_trade_query, (name, price, quantity, trade_id))
    conn.commit()

# 查询数据
def get_trade(trade_id):
    get_trade_query = '''
    SELECT * FROM trade WHERE id = %s
    '''
    cursor.execute(get_trade_query, (trade_id,))
    trade = cursor.fetchone()
    return trade

# 事务处理
def perform_transaction():
    try:
        # 开启事务
        conn.begin()

        # 执行多个SQL语句
        add_trade('Apple', 10.5, 100)
        add_trade('Banana', 5.2, 200)
        delete_trade(2)
        update_trade(1, 'Orange', 8.9, 150)

        # 提交事务
        conn.commit()
        print('Transaction committed successfully.')
    except:
        # 回滚事务
        conn.rollback()
        print('Transaction rolled back.')

# 测试代码
add_trade('Apple', 10.5, 100)
add_trade('Banana', 5.2, 200)
trade = get_trade(1)
print(trade)

update_trade(1, 'Orange', 8.9, 150)
trade = get_trade(1)
print(trade)

delete_trade(2)
trade = get_trade(2)
print(trade)

perform_transaction()

# 关闭数据库连接
cursor.close()
conn.close()

请注意，代码中的host、user、password和database需要根据实际情况进行修改，以连接到正确的 MySQL 数据库服务器和数据库。