{"id":199619,"date":"2025-05-06T08:57:37","date_gmt":"2025-05-06T00:57:37","guid":{"rendered":"https:\/\/server.hk\/cnblog\/199619\/"},"modified":"2025-05-06T08:57:37","modified_gmt":"2025-05-06T00:57:37","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8sql%e8%af%ad%e5%8f%a5%e5%9c%a8mysql%e4%b8%ad%e8%bf%9b%e8%a1%8c%e6%95%b0%e6%8d%ae%e6%a0%a1%e9%aa%8c%e5%92%8c%e5%ae%8c%e6%95%b4%e6%80%a7%e7%ba%a6%e6%9d%9f%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/199619\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528SQL\u8bed\u53e5\u5728MySQL\u4e2d\u8fdb\u884c\u6570\u636e\u6821\u9a8c\u548c\u5b8c\u6574\u6027\u7ea6\u675f\uff1f"},"content":{"rendered":"

<\/b> <\/p>\n

\u5982\u4f55\u4f7f\u7528SQL\u8bed\u53e5\u5728MySQL\u4e2d\u8fdb\u884c\u6570\u636e\u6821\u9a8c\u548c\u5b8c\u6574\u6027\u7ea6\u675f\uff1f<\/h1>\n

\u5b66\u4e60\u8981\u52aa\u529b\uff0c\u4f46\u662f\u4e0d\u8981\u6025\uff01\u4eca\u5929\u7684\u8fd9\u7bc7\u6587\u7ae0\u5c06\u4f1a\u4ecb\u7ecd\u5230\u7b49\u7b49\u77e5\u8bc6\u70b9\uff0c\u5982\u679c\u4f60\u60f3\u6df1\u5165\u5b66\u4e60\uff0c\u53ef\u4ee5\u5173\u6ce8\u6211\uff01\u6211\u4f1a\u6301\u7eed\u66f4\u65b0\u76f8\u5173\u6587\u7ae0\u7684\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u90fd\u80fd\u6709\u6240\u5e2e\u52a9\uff01<\/p>\n

\u5982\u4f55\u4f7f\u7528SQL\u8bed\u53e5\u5728MySQL\u4e2d\u8fdb\u884c\u6570\u636e\u6821\u9a8c\u548c\u5b8c\u6574\u6027\u7ea6\u675f\uff1f<\/p>\n

\u6570\u636e\u6821\u9a8c\u548c\u5b8c\u6574\u6027\u7ea6\u675f\u662f\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf\u4e2d\u5e38\u7528\u7684\u65b9\u6cd5\uff0c\u7528\u4e8e\u786e\u4fdd\u6570\u636e\u7684\u6b63\u786e\u6027\u548c\u5b8c\u6574\u6027\u3002\u5728MySQL\u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528SQL\u8bed\u53e5\u6765\u5b9e\u73b0\u8fd9\u4e9b\u7ea6\u675f\u3002\u672c\u6587\u5c06\u4ecb\u7ecd\u5982\u4f55\u4f7f\u7528SQL\u8bed\u53e5\u5728MySQL\u4e2d\u8fdb\u884c\u6570\u636e\u6821\u9a8c\u548c\u5b8c\u6574\u6027\u7ea6\u675f\uff0c\u5e76\u63d0\u4f9b\u5177\u4f53\u7684\u4ee3\u7801\u793a\u4f8b\u3002<\/p>\n

\u4e00\u3001\u4f7f\u7528CHECK\u7ea6\u675f\u8fdb\u884c\u6570\u636e\u6821\u9a8c<\/p>\n

CHECK\u7ea6\u675f\u7528\u4e8e\u5728\u63d2\u5165\u6216\u66f4\u65b0\u6570\u636e\u65f6\u5bf9\u7279\u5b9a\u5217\u7684\u503c\u8fdb\u884c\u9a8c\u8bc1\u3002\u4ee5\u4e0b\u662f\u4e00\u4e2a\u4f7f\u7528CHECK\u7ea6\u675f\u7684\u793a\u4f8b\uff1a<\/p>\n

CREATE TABLE Students (\n    student_id INT PRIMARY KEY,\n    student_name VARCHAR(50),\n    age INT,\n    CONSTRAINT check_age CHECK (age >= 18)\n);<\/pre>\n
\u4e0a\u8ff0\u793a\u4f8b\u4e2d\uff0c\u6211\u4eec\u521b\u5efa\u4e86\u4e00\u4e2a\u540d\u4e3aStudents\u7684\u8868\uff0c\u5176\u4e2d\u5305\u542bstudent_id\u3001student_name\u548cage\u4e09\u4e2a\u5217\u3002\u901a\u8fc7\u5728age\u5217\u4e0a\u6dfb\u52a0CHECK\u7ea6\u675f\uff0c\u6211\u4eec\u786e\u4fdd\u6240\u6709\u63d2\u5165\u6216\u66f4\u65b0\u64cd\u4f5c\u4e2d\u7684age\u503c\u90fd\u5fc5\u987b\u5927\u4e8e\u7b49\u4e8e18\u3002<\/p>\n
\u4e8c\u3001\u4f7f\u7528UNIQUE\u7ea6\u675f\u8fdb\u884c\u552f\u4e00\u6027\u7ea6\u675f<\/p>\n
UNIQUE\u7ea6\u675f\u7528\u4e8e\u786e\u4fdd\u5217\u4e2d\u7684\u6bcf\u4e2a\u503c\u90fd\u662f\u552f\u4e00\u7684\u3002\u4ee5\u4e0b\u662f\u4e00\u4e2a\u4f7f\u7528UNIQUE\u7ea6\u675f\u7684\u793a\u4f8b\uff1a<\/p>\n
CREATE TABLE Employees (\n    employee_id INT PRIMARY KEY,\n    employee_name VARCHAR(50),\n    email VARCHAR(50) UNIQUE\n);<\/pre>\n
\u4e0a\u8ff0\u793a\u4f8b\u4e2d\uff0c\u6211\u4eec\u521b\u5efa\u4e86\u4e00\u4e2a\u540d\u4e3aEmployees\u7684\u8868\uff0c\u5176\u4e2d\u5305\u542bemployee_id\u3001employee_name\u548cemail\u4e09\u4e2a\u5217\u3002\u901a\u8fc7\u5728email\u5217\u4e0a\u6dfb\u52a0UNIQUE\u7ea6\u675f\uff0c\u6211\u4eec\u786e\u4fdd\u63d2\u5165\u6216\u66f4\u65b0\u64cd\u4f5c\u4e2d\u7684email\u503c\u662f\u552f\u4e00\u7684\u3002<\/p>\n
\u4e09\u3001\u4f7f\u7528FOREIGN KEY\u7ea6\u675f\u8fdb\u884c\u5916\u952e\u7ea6\u675f<\/p>\n
FOREIGN KEY\u7ea6\u675f\u7528\u4e8e\u786e\u4fdd\u8868\u4e2d\u7684\u5916\u952e\u5217\u5f15\u7528\u53e6\u4e00\u4e2a\u8868\u4e2d\u7684\u4e3b\u952e\u5217\u3002\u4ee5\u4e0b\u662f\u4e00\u4e2a\u4f7f\u7528FOREIGN KEY\u7ea6\u675f\u7684\u793a\u4f8b\uff1a<\/p>\n
CREATE TABLE Orders (\n    order_id INT PRIMARY KEY,\n    order_date DATE,\n    customer_id INT,\n    CONSTRAINT fk_customer_id FOREIGN KEY (customer_id) REFERENCES Customers(customer_id)\n);<\/pre>\n
\u4e0a\u8ff0\u793a\u4f8b\u4e2d\uff0c\u6211\u4eec\u521b\u5efa\u4e86\u4e00\u4e2a\u540d\u4e3aOrders\u7684\u8868\uff0c\u5176\u4e2d\u5305\u542border_id\u3001order_date\u548ccustomer_id\u4e09\u4e2a\u5217\u3002\u901a\u8fc7\u5728customer_id\u5217\u4e0a\u6dfb\u52a0FOREIGN KEY\u7ea6\u675f\u5e76\u5f15\u7528Customers\u8868\u7684customer_id\u5217\uff0c\u6211\u4eec\u786e\u4fdd\u63d2\u5165\u6216\u66f4\u65b0\u64cd\u4f5c\u4e2d\u7684customer_id\u503c\u5fc5\u987b\u662f\u6709\u6548\u7684\u3002<\/p>\n
\u56db\u3001\u4f7f\u7528NOT NULL\u7ea6\u675f\u8fdb\u884c\u975e\u7a7a\u7ea6\u675f<\/p>\n
NOT NULL\u7ea6\u675f\u7528\u4e8e\u786e\u4fdd\u5217\u4e2d\u7684\u503c\u4e0d\u4e3a\u7a7a\u3002\u4ee5\u4e0b\u662f\u4e00\u4e2a\u4f7f\u7528NOT NULL\u7ea6\u675f\u7684\u793a\u4f8b\uff1a<\/p>\n
CREATE TABLE Products (\n    product_id INT PRIMARY KEY,\n    product_name VARCHAR(50) NOT NULL,\n    price DECIMAL(10,2) NOT NULL\n);<\/pre>\n
\u4e0a\u8ff0\u793a\u4f8b\u4e2d\uff0c\u6211\u4eec\u521b\u5efa\u4e86\u4e00\u4e2a\u540d\u4e3aProducts\u7684\u8868\uff0c\u5176\u4e2d\u5305\u542bproduct_id\u3001product_name\u548cprice\u4e09\u4e2a\u5217\u3002\u901a\u8fc7\u5728product_name\u548cprice\u5217\u4e0a\u6dfb\u52a0NOT NULL\u7ea6\u675f\uff0c\u6211\u4eec\u786e\u4fdd\u63d2\u5165\u6216\u66f4\u65b0\u64cd\u4f5c\u4e2d\u7684\u8fd9\u4e24\u5217\u7684\u503c\u4e0d\u80fd\u4e3a\u7a7a\u3002<\/p>\n
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\u4eca\u5929\u5e26\u5927\u5bb6\u4e86\u89e3\u4e86\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u5e0c\u671b\u5bf9\u4f60\u6709\u6240\u5e2e\u52a9\uff1b\u5173\u4e8e\u6570\u636e\u5e93\u7684\u6280\u672f\u77e5\u8bc6\u6211\u4eec\u4f1a\u4e00\u70b9\u70b9\u6df1\u5165\u4ecb\u7ecd\uff0c\u6b22\u8fce\u5927\u5bb6\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\uff0c\u4e00\u8d77\u5b66\u4e60\u7f16\u7a0b~<\/p>\n
\n
\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"
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