{"id":144021,"date":"2024-11-01T03:12:20","date_gmt":"2024-10-31T19:12:20","guid":{"rendered":"https:\/\/server.hk\/cnblog\/144021\/"},"modified":"2024-11-01T03:12:21","modified_gmt":"2024-10-31T19:12:21","slug":"sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%86%97%e9%a4%98%e5%8e%9f%e5%9b%a0%e5%8f%8a%e8%a7%a3%e6%b1%ba%e6%96%b9%e6%b3%95-sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%86%97%e9%a4%98","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/144021\/","title":{"rendered":"SQL \u6578\u64da\u5eab\u5197\u9918\u539f\u56e0\u53ca\u89e3\u6c7a\u65b9\u6cd5 (sql \u6578\u64da\u5eab\u5197\u9918)"},"content":{"rendered":"<h1 id=\"sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%86%97%e9%a4%98%e5%8e%9f%e5%9b%a0%e5%8f%8a%e8%a7%a3%e6%b1%ba%e6%96%b9%e6%b3%95-OEsXdukjOb\">SQL \u6578\u64da\u5eab\u5197\u9918\u539f\u56e0\u53ca\u89e3\u6c7a\u65b9\u6cd5<\/h1>\n<p>\u5728\u7576\u4eca\u6578\u64da\u9a45\u52d5\u7684\u4e16\u754c\u4e2d\uff0cSQL \u6578\u64da\u5eab\u662f\u8a31\u591a\u61c9\u7528\u7a0b\u5e8f\u548c\u7db2\u7ad9\u7684\u6838\u5fc3\u7d44\u4ef6\u3002\u7136\u800c\uff0c\u6578\u64da\u5197\u9918\u554f\u984c\u537b\u5e38\u5e38\u56f0\u64fe\u8457\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u3002\u672c\u6587\u5c07\u63a2\u8a0e SQL \u6578\u64da\u5eab\u5197\u9918\u7684\u539f\u56e0\u53ca\u5176\u89e3\u6c7a\u65b9\u6cd5\uff0c\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u548c\u7ba1\u7406\u6578\u64da\u5eab\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af%e6%95%b8%e6%93%9a%e5%86%97%e9%a4%98%ef%bc%9f-OEsXdukjOb\">\u4ec0\u9ebc\u662f\u6578\u64da\u5197\u9918\uff1f<\/h2>\n<p>\u6578\u64da\u5197\u9918\u662f\u6307\u5728\u6578\u64da\u5eab\u4e2d\u91cd\u8907\u5b58\u5132\u76f8\u540c\u7684\u6578\u64da\u3002\u9019\u7a2e\u60c5\u6cc1\u53ef\u80fd\u5c0e\u81f4\u6578\u64da\u4e0d\u4e00\u81f4\u6027\u3001\u589e\u52a0\u5b58\u5132\u6210\u672c\u4ee5\u53ca\u964d\u4f4e\u67e5\u8a62\u6027\u80fd\u3002\u6578\u64da\u5197\u9918\u901a\u5e38\u767c\u751f\u5728\u4ee5\u4e0b\u5e7e\u7a2e\u60c5\u6cc1\u4e0b\uff1a<\/p>\n<ul>\n<li>\u4e0d\u7576\u7684\u6578\u64da\u5eab\u8a2d\u8a08<\/li>\n<li>\u7f3a\u4e4f\u6b63\u898f\u5316<\/li>\n<li>\u591a\u500b\u61c9\u7528\u7a0b\u5e8f\u540c\u6642\u8a2a\u554f\u76f8\u540c\u7684\u6578\u64da<\/li>\n<\/ul>\n<h2 id=\"%e6%95%b8%e6%93%9a%e5%86%97%e9%a4%98%e7%9a%84%e5%8e%9f%e5%9b%a0-OEsXdukjOb\">\u6578\u64da\u5197\u9918\u7684\u539f\u56e0<\/h2>\n<h3 id=\"1-%e4%b8%8d%e7%95%b6%e7%9a%84%e6%95%b8%e6%93%9a%e5%ba%ab%e8%a8%ad%e8%a8%88-OEsXdukjOb\">1. \u4e0d\u7576\u7684\u6578\u64da\u5eab\u8a2d\u8a08<\/h3>\n<p>\u5728\u8a2d\u8a08\u6578\u64da\u5eab\u6642\uff0c\u5982\u679c\u6c92\u6709\u5145\u5206\u8003\u616e\u6578\u64da\u4e4b\u9593\u7684\u95dc\u4fc2\uff0c\u53ef\u80fd\u6703\u5c0e\u81f4\u5197\u9918\u3002\u4f8b\u5982\uff0c\u5c07\u76f8\u540c\u7684\u5ba2\u6236\u4fe1\u606f\u5b58\u5132\u5728\u591a\u500b\u8868\u4e2d\uff0c\u9019\u6a23\u5728\u66f4\u65b0\u5ba2\u6236\u4fe1\u606f\u6642\uff0c\u5fc5\u9808\u5728\u591a\u500b\u5730\u65b9\u9032\u884c\u4fee\u6539\uff0c\u5bb9\u6613\u51fa\u73fe\u4e0d\u4e00\u81f4\u7684\u60c5\u6cc1\u3002<\/p>\n<h3 id=\"2-%e7%bc%ba%e4%b9%8f%e6%ad%a3%e8%a6%8f%e5%8c%96-OEsXdukjOb\">2. \u7f3a\u4e4f\u6b63\u898f\u5316<\/h3>\n<p>\u6b63\u898f\u5316\u662f\u6307\u901a\u904e\u5c07\u6578\u64da\u5206\u89e3\u6210\u66f4\u5c0f\u7684\u3001\u76f8\u4e92\u95dc\u806f\u7684\u8868\u4f86\u6d88\u9664\u5197\u9918\u7684\u904e\u7a0b\u3002\u82e5\u6578\u64da\u5eab\u672a\u7d93\u904e\u6b63\u898f\u5316\uff0c\u5247\u53ef\u80fd\u6703\u51fa\u73fe\u91cd\u8907\u6578\u64da\u3002\u4f8b\u5982\uff0c\u5c07\u5ba2\u6236\u7684\u8a02\u55ae\u548c\u5730\u5740\u4fe1\u606f\u5b58\u5132\u5728\u540c\u4e00\u8868\u4e2d\uff0c\u53ef\u80fd\u6703\u5c0e\u81f4\u76f8\u540c\u5730\u5740\u7684\u91cd\u8907\u5b58\u5132\u3002<\/p>\n<h3 id=\"3-%e5%a4%9a%e5%80%8b%e6%87%89%e7%94%a8%e7%a8%8b%e5%ba%8f%e5%90%8c%e6%99%82%e8%a8%aa%e5%95%8f%e7%9b%b8%e5%90%8c%e7%9a%84%e6%95%b8%e6%93%9a-OEsXdukjOb\">3. \u591a\u500b\u61c9\u7528\u7a0b\u5e8f\u540c\u6642\u8a2a\u554f\u76f8\u540c\u7684\u6578\u64da<\/h3>\n<p>\u5728\u5927\u578b\u7cfb\u7d71\u4e2d\uff0c\u53ef\u80fd\u6709\u591a\u500b\u61c9\u7528\u7a0b\u5e8f\u540c\u6642\u8a2a\u554f\u548c\u4fee\u6539\u76f8\u540c\u7684\u6578\u64da\u3002\u5982\u679c\u9019\u4e9b\u61c9\u7528\u7a0b\u5e8f\u6c92\u6709\u826f\u597d\u7684\u5354\u8abf\u6a5f\u5236\uff0c\u5247\u53ef\u80fd\u6703\u5c0e\u81f4\u6578\u64da\u5197\u9918\u548c\u4e0d\u4e00\u81f4\u6027\u3002<\/p>\n<h2 id=\"%e8%a7%a3%e6%b1%ba%e6%95%b8%e6%93%9a%e5%86%97%e9%a4%98%e7%9a%84%e6%96%b9%e6%b3%95-OEsXdukjOb\">\u89e3\u6c7a\u6578\u64da\u5197\u9918\u7684\u65b9\u6cd5<\/h2>\n<h3 id=\"1-%e6%95%b8%e6%93%9a%e5%ba%ab%e6%ad%a3%e8%a6%8f%e5%8c%96-OEsXdukjOb\">1. \u6578\u64da\u5eab\u6b63\u898f\u5316<\/h3>\n<p>\u6b63\u898f\u5316\u662f\u89e3\u6c7a\u6578\u64da\u5197\u9918\u7684\u6700\u6709\u6548\u65b9\u6cd5\u4e4b\u4e00\u3002\u901a\u904e\u5c07\u6578\u64da\u5206\u89e3\u70ba\u591a\u500b\u8868\uff0c\u4e26\u4f7f\u7528\u5916\u9375\u4f86\u5efa\u7acb\u8868\u4e4b\u9593\u7684\u95dc\u4fc2\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u6d88\u9664\u5197\u9918\u3002\u4f8b\u5982\uff0c\u5c07\u5ba2\u6236\u4fe1\u606f\u548c\u8a02\u55ae\u4fe1\u606f\u5206\u958b\u5b58\u5132\uff0c\u4e26\u901a\u904e\u5ba2\u6236ID\u9032\u884c\u95dc\u806f\u3002<\/p>\n<pre><code>CREATE TABLE Customers (\n    CustomerID INT PRIMARY KEY,\n    CustomerName VARCHAR(100),\n    ContactEmail VARCHAR(100)\n);\n\nCREATE TABLE Orders (\n    OrderID INT PRIMARY KEY,\n    OrderDate DATE,\n    CustomerID INT,\n    FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID)\n);<\/code><\/pre>\n<h3 id=\"2-%e4%bd%bf%e7%94%a8%e7%b4%84%e6%9d%9f%e6%a2%9d%e4%bb%b6-OEsXdukjOb\">2. \u4f7f\u7528\u7d04\u675f\u689d\u4ef6<\/h3>\n<p>\u5728\u6578\u64da\u5eab\u4e2d\u4f7f\u7528\u7d04\u675f\u689d\u4ef6\uff08\u5982\u552f\u4e00\u6027\u7d04\u675f\uff09\u53ef\u4ee5\u9632\u6b62\u91cd\u8907\u6578\u64da\u7684\u63d2\u5165\u3002\u4f8b\u5982\uff0c\u53ef\u4ee5\u5728\u5ba2\u6236\u8868\u4e2d\u8a2d\u7f6e\u96fb\u5b50\u90f5\u4ef6\u5730\u5740\u7684\u552f\u4e00\u6027\u7d04\u675f\uff0c\u9019\u6a23\u5c31\u53ef\u4ee5\u907f\u514d\u91cd\u8907\u7684\u5ba2\u6236\u8a18\u9304\u3002<\/p>\n<pre><code>ALTER TABLE Customers\nADD CONSTRAINT UC_Email UNIQUE (ContactEmail);<\/code><\/pre>\n<h3 id=\"3-%e5%ae%9a%e6%9c%9f%e6%95%b8%e6%93%9a%e6%b8%85%e7%90%86-OEsXdukjOb\">3. \u5b9a\u671f\u6578\u64da\u6e05\u7406<\/h3>\n<p>\u5b9a\u671f\u6aa2\u67e5\u548c\u6e05\u7406\u6578\u64da\u5eab\u4e2d\u7684\u5197\u9918\u6578\u64da\u4e5f\u662f\u4e00\u500b\u91cd\u8981\u7684\u7ba1\u7406\u63aa\u65bd\u3002\u53ef\u4ee5\u901a\u904e\u7de8\u5beb\u67e5\u8a62\u4f86\u8b58\u5225\u548c\u522a\u9664\u91cd\u8907\u7684\u8a18\u9304\uff0c\u5f9e\u800c\u4fdd\u6301\u6578\u64da\u5eab\u7684\u6574\u6f54\u3002<\/p>\n<pre><code>DELETE FROM Customers\nWHERE CustomerID NOT IN (\n    SELECT MIN(CustomerID)\n    FROM Customers\n    GROUP BY ContactEmail\n);<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-OEsXdukjOb\">\u7e3d\u7d50<\/h2>\n<p>SQL \u6578\u64da\u5eab\u5197\u9918\u662f\u4e00\u500b\u5e38\u898b\u7684\u554f\u984c\uff0c\u53ef\u80fd\u6703\u5c0e\u81f4\u6578\u64da\u4e0d\u4e00\u81f4\u6027\u548c\u6027\u80fd\u4e0b\u964d\u3002\u901a\u904e\u6b63\u898f\u5316\u3001\u4f7f\u7528\u7d04\u675f\u689d\u4ef6\u4ee5\u53ca\u5b9a\u671f\u6578\u64da\u6e05\u7406\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u89e3\u6c7a\u9019\u4e00\u554f\u984c\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u7ba1\u7406\u7684\u4f01\u696d\u4f86\u8aaa\uff0c\u9078\u64c7\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u6216 <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u89e3\u6c7a\u65b9\u6848\u81f3\u95dc\u91cd\u8981\uff0c\u4ee5\u78ba\u4fdd\u6578\u64da\u5eab\u7684\u7a69\u5b9a\u6027\u548c\u53ef\u9760\u6027\u3002\u4e86\u89e3\u66f4\u591a\u95dc\u65bc <a href=\"https:\/\/server.hk\">\u96f2\u4f3a\u670d\u5668<\/a> \u7684\u4fe1\u606f\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22SQL\u6578\u64da\u5eab\u5197\u9918\u7684\u539f\u56e0\u53ca\u6709\u6548\u89e3\u6c7a\u65b9\u6cd5\uff0c\u63d0\u5347\u6578\u64da\u7ba1\u7406\u6548\u7387\uff0c\u6e1b\u5c11\u5b58\u5132\u6d6a\u8cbb\uff0c\u78ba\u4fdd\u6578\u64da\u4e00\u81f4\u6027\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-144021","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/144021","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=144021"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/144021\/revisions"}],"predecessor-version":[{"id":144022,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/144021\/revisions\/144022"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=144021"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=144021"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=144021"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}