{"id":160015,"date":"2024-11-03T19:34:20","date_gmt":"2024-11-03T11:34:20","guid":{"rendered":"https:\/\/server.hk\/cnblog\/160015\/"},"modified":"2024-11-03T19:34:21","modified_gmt":"2024-11-03T11:34:21","slug":"mssql-%e6%95%99%e7%a8%8b-sql-%e7%b4%84%e6%9d%9f%ef%bc%88constraints%ef%bc%89","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/160015\/","title":{"rendered":"MSSQL \u6559\u7a0b SQL \u7d04\u675f\uff08Constraints\uff09"},"content":{"rendered":"<h1 id=\"mssql-%e6%95%99%e7%a8%8b-sql-%e7%b4%84%e6%9d%9f%ef%bc%88constraints%ef%bc%89-gcWeYIjkAB\">MSSQL \u6559\u7a0b SQL \u7d04\u675f\uff08Constraints\uff09<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u8a2d\u8a08\u4e2d\uff0c\u7d04\u675f\uff08Constraints\uff09\u662f\u7528\u4f86\u9650\u5236\u8cc7\u6599\u8868\u4e2d\u8cc7\u6599\u7684\u6709\u6548\u6027\u548c\u5b8c\u6574\u6027\u7684\u91cd\u8981\u5de5\u5177\u3002Microsoft SQL Server\uff08MSSQL\uff09\u63d0\u4f9b\u4e86\u591a\u7a2e\u7d04\u675f\u985e\u578b\uff0c\u4ee5\u78ba\u4fdd\u8cc7\u6599\u7684\u6b63\u78ba\u6027\u548c\u4e00\u81f4\u6027\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e MSSQL \u4e2d\u7684\u5404\u7a2e\u7d04\u675f\u985e\u578b\u53ca\u5176\u4f7f\u7528\u65b9\u6cd5\u3002<\/p>\n<h2 id=\"%e7%b4%84%e6%9d%9f%e7%9a%84%e9%a1%9e%e5%9e%8b-gcWeYIjkAB\">\u7d04\u675f\u7684\u985e\u578b<\/h2>\n<p>MSSQL \u4e2d\u7684\u7d04\u675f\u4e3b\u8981\u53ef\u4ee5\u5206\u70ba\u4ee5\u4e0b\u5e7e\u7a2e\u985e\u578b\uff1a<\/p>\n<ul>\n<li><strong>\u4e3b\u9375\u7d04\u675f\uff08PRIMARY KEY\uff09<\/strong><\/li>\n<li><strong>\u5916\u9375\u7d04\u675f\uff08FOREIGN KEY\uff09<\/strong><\/li>\n<li><strong>\u552f\u4e00\u7d04\u675f\uff08UNIQUE\uff09<\/strong><\/li>\n<li><strong>\u6aa2\u67e5\u7d04\u675f\uff08CHECK\uff09<\/strong><\/li>\n<li><strong>\u9810\u8a2d\u7d04\u675f\uff08DEFAULT\uff09<\/strong><\/li>\n<\/ul>\n<h3 id=\"1-%e4%b8%bb%e9%8d%b5%e7%b4%84%e6%9d%9f%ef%bc%88primary-key%ef%bc%89-gcWeYIjkAB\">1. \u4e3b\u9375\u7d04\u675f\uff08PRIMARY KEY\uff09<\/h3>\n<p>\u4e3b\u9375\u7d04\u675f\u7528\u65bc\u552f\u4e00\u6a19\u8b58\u8cc7\u6599\u8868\u4e2d\u7684\u6bcf\u4e00\u884c\u3002\u6bcf\u500b\u8cc7\u6599\u8868\u53ea\u80fd\u6709\u4e00\u500b\u4e3b\u9375\uff0c\u4e14\u4e3b\u9375\u7684\u503c\u4e0d\u80fd\u70ba\u7a7a\u3002\u4ee5\u4e0b\u662f\u5275\u5efa\u4e3b\u9375\u7d04\u675f\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>CREATE TABLE Customers (\n    CustomerID int PRIMARY KEY,\n    CustomerName varchar(255) NOT NULL\n);<\/code><\/pre>\n<h3 id=\"2-%e5%a4%96%e9%8d%b5%e7%b4%84%e6%9d%9f%ef%bc%88foreign-key%ef%bc%89-gcWeYIjkAB\">2. \u5916\u9375\u7d04\u675f\uff08FOREIGN KEY\uff09<\/h3>\n<p>\u5916\u9375\u7d04\u675f\u7528\u65bc\u5efa\u7acb\u5169\u500b\u8cc7\u6599\u8868\u4e4b\u9593\u7684\u95dc\u806f\u3002\u5b83\u78ba\u4fdd\u5728\u4e00\u500b\u8cc7\u6599\u8868\u4e2d\u7684\u67d0\u500b\u6b04\u4f4d\u7684\u503c\u5fc5\u9808\u5b58\u5728\u65bc\u53e6\u4e00\u500b\u8cc7\u6599\u8868\u7684\u4e3b\u9375\u4e2d\u3002\u4ee5\u4e0b\u662f\u5275\u5efa\u5916\u9375\u7d04\u675f\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>CREATE TABLE Orders (\n    OrderID int PRIMARY KEY,\n    CustomerID int,\n    FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID)\n);<\/code><\/pre>\n<h3 id=\"3-%e5%94%af%e4%b8%80%e7%b4%84%e6%9d%9f%ef%bc%88unique%ef%bc%89-gcWeYIjkAB\">3. \u552f\u4e00\u7d04\u675f\uff08UNIQUE\uff09<\/h3>\n<p>\u552f\u4e00\u7d04\u675f\u78ba\u4fdd\u8cc7\u6599\u8868\u4e2d\u7684\u67d0\u500b\u6b04\u4f4d\u7684\u503c\u662f\u552f\u4e00\u7684\uff0c\u9019\u610f\u5473\u8457\u4e0d\u53ef\u4ee5\u6709\u91cd\u8907\u7684\u503c\u3002\u8207\u4e3b\u9375\u4e0d\u540c\u7684\u662f\uff0c\u552f\u4e00\u7d04\u675f\u7684\u6b04\u4f4d\u53ef\u4ee5\u5305\u542b\u7a7a\u503c\u3002\u4ee5\u4e0b\u662f\u5275\u5efa\u552f\u4e00\u7d04\u675f\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>CREATE TABLE Employees (\n    EmployeeID int PRIMARY KEY,\n    Email varchar(255) UNIQUE\n);<\/code><\/pre>\n<h3 id=\"4-%e6%aa%a2%e6%9f%a5%e7%b4%84%e6%9d%9f%ef%bc%88check%ef%bc%89-gcWeYIjkAB\">4. \u6aa2\u67e5\u7d04\u675f\uff08CHECK\uff09<\/h3>\n<p>\u6aa2\u67e5\u7d04\u675f\u7528\u65bc\u9650\u5236\u6b04\u4f4d\u4e2d\u7684\u503c\uff0c\u78ba\u4fdd\u5176\u7b26\u5408\u7279\u5b9a\u689d\u4ef6\u3002\u4ee5\u4e0b\u662f\u5275\u5efa\u6aa2\u67e5\u7d04\u675f\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>CREATE TABLE Products (\n    ProductID int PRIMARY KEY,\n    Price decimal CHECK (Price &gt;= 0)\n);<\/code><\/pre>\n<h3 id=\"5-%e9%a0%90%e8%a8%ad%e7%b4%84%e6%9d%9f%ef%bc%88default%ef%bc%89-gcWeYIjkAB\">5. \u9810\u8a2d\u7d04\u675f\uff08DEFAULT\uff09<\/h3>\n<p>\u9810\u8a2d\u7d04\u675f\u7528\u65bc\u70ba\u6b04\u4f4d\u6307\u5b9a\u4e00\u500b\u9810\u8a2d\u503c\uff0c\u7576\u63d2\u5165\u8cc7\u6599\u6642\u5982\u679c\u672a\u63d0\u4f9b\u8a72\u6b04\u4f4d\u7684\u503c\uff0c\u5247\u6703\u4f7f\u7528\u9810\u8a2d\u503c\u3002\u4ee5\u4e0b\u662f\u5275\u5efa\u9810\u8a2d\u7d04\u675f\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>CREATE TABLE Orders (\n    OrderID int PRIMARY KEY,\n    OrderDate datetime DEFAULT GETDATE()\n);<\/code><\/pre>\n<h2 id=\"%e7%b4%84%e6%9d%9f%e7%9a%84%e7%ae%a1%e7%90%86-gcWeYIjkAB\">\u7d04\u675f\u7684\u7ba1\u7406<\/h2>\n<p>\u5728 MSSQL \u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528 ALTER TABLE \u8a9e\u53e5\u4f86\u6dfb\u52a0\u6216\u522a\u9664\u7d04\u675f\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u70ba\u5df2\u5b58\u5728\u7684\u8cc7\u6599\u8868\u6dfb\u52a0\u552f\u4e00\u7d04\u675f\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u8a9e\u53e5\uff1a<\/p>\n<pre><code>ALTER TABLE Employees\nADD CONSTRAINT UQ_Email UNIQUE (Email);<\/code><\/pre>\n<p>\u82e5\u8981\u522a\u9664\u7d04\u675f\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u8a9e\u53e5\uff1a<\/p>\n<pre><code>ALTER TABLE Employees\nDROP CONSTRAINT UQ_Email;<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-gcWeYIjkAB\">\u7e3d\u7d50<\/h2>\n<p>\u7d04\u675f\u5728 MSSQL \u4e2d\u626e\u6f14\u8457\u81f3\u95dc\u91cd\u8981\u7684\u89d2\u8272\uff0c\u5e6b\u52a9\u78ba\u4fdd\u8cc7\u6599\u7684\u5b8c\u6574\u6027\u548c\u4e00\u81f4\u6027\u3002\u900f\u904e\u4e3b\u9375\u3001\u5916\u9375\u3001\u552f\u4e00\u3001\u6aa2\u67e5\u548c\u9810\u8a2d\u7d04\u675f\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u6709\u6548\u5730\u7ba1\u7406\u8cc7\u6599\u5eab\u4e2d\u7684\u8cc7\u6599\u3002\u4e86\u89e3\u9019\u4e9b\u7d04\u675f\u7684\u4f7f\u7528\u65b9\u6cd5\uff0c\u5c07\u6709\u52a9\u65bc\u8a2d\u8a08\u51fa\u66f4\u70ba\u7a69\u5065\u7684\u8cc7\u6599\u5eab\u7cfb\u7d71\u3002<\/p>\n<p>\u5982\u9700\u9032\u4e00\u6b65\u4e86\u89e3\u5982\u4f55\u5728\u9999\u6e2f\u4f7f\u7528 <a href=\"https:\/\/server.hk\">VPS<\/a> \u9032\u884c\u8cc7\u6599\u5eab\u7ba1\u7406\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u8cc7\u8a0a\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22 MSSQL \u6559\u7a0b\u4e2d\u7684 SQL \u7d04\u675f\uff08Constraints\uff09\uff0c\u5b78\u7fd2\u5982\u4f55\u6709\u6548\u7ba1\u7406\u6578\u64da\u5b8c\u6574\u6027\u548c\u7d04\u675f\u689d\u4ef6\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-160015","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160015","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=160015"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160015\/revisions"}],"predecessor-version":[{"id":160016,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160015\/revisions\/160016"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=160015"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=160015"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=160015"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}