{"id":175503,"date":"2024-11-08T06:25:18","date_gmt":"2024-11-07T22:25:18","guid":{"rendered":"https:\/\/server.hk\/cnblog\/175503\/"},"modified":"2024-11-08T06:25:19","modified_gmt":"2024-11-07T22:25:19","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8%e6%95%b8%e6%93%9a%e5%ba%ab%e8%a8%88%e7%ae%97%e7%b8%bd%e5%83%b9%ef%bc%9f-%e6%95%b8%e6%93%9a%e5%ba%ab%e8%a8%88%e7%ae%97%e7%b8%bd%e5%83%b9","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/175503\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528\u6578\u64da\u5eab\u8a08\u7b97\u7e3d\u50f9\uff1f (\u6578\u64da\u5eab\u8a08\u7b97\u7e3d\u50f9)"},"content":{"rendered":"

\u5982\u4f55\u4f7f\u7528\u6578\u64da\u5eab\u8a08\u7b97\u7e3d\u50f9\uff1f (\u6578\u64da\u5eab\u8a08\u7b97\u7e3d\u50f9)<\/h1>\n

\u5728\u73fe\u4ee3\u5546\u696d\u74b0\u5883\u4e2d\uff0c\u6578\u64da\u5eab\u7684\u4f7f\u7528\u5df2\u6210\u70ba\u4e0d\u53ef\u6216\u7f3a\u7684\u4e00\u90e8\u5206\u3002\u7121\u8ad6\u662f\u96fb\u5b50\u5546\u52d9\u5e73\u53f0\u9084\u662f\u4f01\u696d\u5167\u90e8\u7cfb\u7d71\uff0c\u8a08\u7b97\u7e3d\u50f9\u7684\u529f\u80fd\u90fd\u662f\u4e00\u500b\u57fa\u672c\u9700\u6c42\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u4f7f\u7528\u6578\u64da\u5eab\u4f86\u8a08\u7b97\u7e3d\u50f9\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5be6\u7528\u7684\u793a\u4f8b\u548c\u4ee3\u78bc\u7247\u6bb5\u3002<\/p>\n

\u6578\u64da\u5eab\u7d50\u69cb\u8a2d\u8a08<\/h2>\n

\u5728\u958b\u59cb\u8a08\u7b97\u7e3d\u50f9\u4e4b\u524d\uff0c\u9996\u5148\u9700\u8981\u8a2d\u8a08\u4e00\u500b\u5408\u9069\u7684\u6578\u64da\u5eab\u7d50\u69cb\u3002\u901a\u5e38\uff0c\u6d89\u53ca\u5230\u7684\u8868\u683c\u5305\u62ec\u7522\u54c1\u8868\u548c\u8a02\u55ae\u8868\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u6578\u64da\u5eab\u7d50\u69cb\u793a\u4f8b\uff1a<\/p>\n

\nCREATE TABLE products (\n    product_id INT PRIMARY KEY,\n    product_name VARCHAR(100),\n    price DECIMAL(10, 2)\n);\n\nCREATE TABLE orders (\n    order_id INT PRIMARY KEY,\n    product_id INT,\n    quantity INT,\n    FOREIGN KEY (product_id) REFERENCES products(product_id)\n);\n<\/pre>\n
\u5728\u9019\u500b\u7d50\u69cb\u4e2d\uff0cproducts<\/code> \u8868\u5b58\u5132\u7522\u54c1\u7684\u57fa\u672c\u4fe1\u606f\uff0c\u5305\u62ec\u7522\u54c1ID\u3001\u540d\u7a31\u548c\u50f9\u683c\uff1b\u800c orders<\/code> \u8868\u5247\u8a18\u9304\u6bcf\u500b\u8a02\u55ae\u7684\u7522\u54c1ID\u548c\u6578\u91cf\u3002<\/p>\n
\u8a08\u7b97\u7e3d\u50f9\u7684SQL\u67e5\u8a62<\/h2>\n
\u4e00\u65e6\u6578\u64da\u5eab\u7d50\u69cb\u8a2d\u8a08\u5b8c\u6210\uff0c\u63a5\u4e0b\u4f86\u5c31\u53ef\u4ee5\u4f7f\u7528SQL\u67e5\u8a62\u4f86\u8a08\u7b97\u7e3d\u50f9\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\u67e5\u8a62\uff0c\u8a72\u67e5\u8a62\u5c07\u6839\u64da\u8a02\u55ae\u8868\u4e2d\u7684\u6578\u64da\u8a08\u7b97\u6bcf\u500b\u8a02\u55ae\u7684\u7e3d\u50f9\uff1a<\/p>\n
\nSELECT o.order_id, SUM(p.price * o.quantity) AS total_price\nFROM orders o\nJOIN products p ON o.product_id = p.product_id\nGROUP BY o.order_id;\n<\/pre>\n
\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u4f7f\u7528\u4e86 JOIN<\/code> \u4f86\u5c07 orders<\/code> \u8868\u548c products<\/code> \u8868\u9023\u63a5\u8d77\u4f86\uff0c\u7136\u5f8c\u8a08\u7b97\u6bcf\u500b\u8a02\u55ae\u7684\u7e3d\u50f9\u3002SUM<\/code> \u51fd\u6578\u7528\u65bc\u8a08\u7b97\u6bcf\u500b\u8a02\u55ae\u4e2d\u6240\u6709\u7522\u54c1\u7684\u7e3d\u50f9\u3002<\/p>\n
\u4f7f\u7528\u7de8\u7a0b\u8a9e\u8a00\u9032\u884c\u8a08\u7b97<\/h2>\n
\u9664\u4e86\u4f7f\u7528SQL\u67e5\u8a62\u5916\uff0c\u9084\u53ef\u4ee5\u4f7f\u7528\u7de8\u7a0b\u8a9e\u8a00\u4f86\u8a08\u7b97\u7e3d\u50f9\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528Python\u548cSQLAlchemy\u7684\u793a\u4f8b\uff1a<\/p>\n
\nfrom sqlalchemy import create_engine, Column, Integer, String, Numeric, ForeignKey\nfrom sqlalchemy.ext.declarative import declarative_base\nfrom sqlalchemy.orm import sessionmaker\n\nBase = declarative_base()\n\nclass Product(Base):\n    __tablename__ = 'products'\n    product_id = Column(Integer, primary_key=True)\n    product_name = Column(String)\n    price = Column(Numeric)\n\nclass Order(Base):\n    __tablename__ = 'orders'\n    order_id = Column(Integer, primary_key=True)\n    product_id = Column(Integer, ForeignKey('products.product_id'))\n    quantity = Column(Integer)\n\nengine = create_engine('sqlite:\/\/\/example.db')\nSession = sessionmaker(bind=engine)\nsession = Session()\n\ndef calculate_total_price(order_id):\n    total_price = session.query(Order).filter(Order.order_id == order_id).join(Product).with_entities((Product.price * Order.quantity).label('total')).scalar()\n    return total_price\n\nprint(calculate_total_price(1))\n<\/pre>\n
\u5728\u9019\u500b\u793a\u4f8b\u4e2d\uff0c\u6211\u5011\u5b9a\u7fa9\u4e86 Product<\/code> \u548c Order<\/code> \u985e\uff0c\u4e26\u4f7f\u7528 SQLAlchemy \u4f86\u67e5\u8a62\u6578\u64da\u5eab\u3002calculate_total_price<\/code> \u51fd\u6578\u6839\u64da\u8a02\u55aeID\u8a08\u7b97\u7e3d\u50f9\u3002<\/p>\n
\u7d50\u8ad6<\/h2>\n
\u4f7f\u7528\u6578\u64da\u5eab\u8a08\u7b97\u7e3d\u50f9\u662f\u4e00\u500b\u91cd\u8981\u7684\u529f\u80fd\uff0c\u7121\u8ad6\u662f\u5728\u96fb\u5b50\u5546\u52d9\u9084\u662f\u5176\u4ed6\u696d\u52d9\u61c9\u7528\u4e2d\u3002\u901a\u904e\u8a2d\u8a08\u5408\u9069\u7684\u6578\u64da\u5eab\u7d50\u69cb\u548c\u4f7f\u7528SQL\u67e5\u8a62\u6216\u7de8\u7a0b\u8a9e\u8a00\uff0c\u6211\u5011\u53ef\u4ee5\u8f15\u9b06\u5730\u5be6\u73fe\u9019\u4e00\u529f\u80fd\u3002\u9019\u4e0d\u50c5\u63d0\u9ad8\u4e86\u8a08\u7b97\u7684\u6e96\u78ba\u6027\uff0c\u9084\u80fd\u5920\u6709\u6548\u5730\u7ba1\u7406\u548c\u5206\u6790\u6578\u64da\u3002<\/p>\n
\u5982\u679c\u60a8\u5c0d\u65bc\u5982\u4f55\u5728\u60a8\u7684\u696d\u52d9\u4e2d\u5be6\u65bd\u9019\u4e9b\u6280\u8853\u6709\u8208\u8da3\uff0c\u6216\u8005\u9700\u8981\u66f4\u9ad8\u6548\u7684\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528 \u9999\u6e2fVPS<\/a> \u4f86\u652f\u6301\u60a8\u7684\u6578\u64da\u5eab\u9700\u6c42\u3002\u7121\u8ad6\u662f \u4e91\u670d\u52a1\u5668<\/a> \u9084\u662f\u5176\u4ed6\u670d\u52d9\uff0cServer.HK \u90fd\u80fd\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
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