{"id":183622,"date":"2024-11-10T06:21:16","date_gmt":"2024-11-09T22:21:16","guid":{"rendered":"https:\/\/server.hk\/cnblog\/183622\/"},"modified":"2024-11-10T06:21:17","modified_gmt":"2024-11-09T22:21:17","slug":"%e4%bd%bf%e7%94%a8c-linq%e5%af%a6%e7%8f%be%e6%95%b8%e6%93%9a%e5%ba%ab%e5%8e%bb%e9%87%8d%e7%ae%a1%e7%90%86-c-linq-%e4%b8%8d%e9%87%8d%e8%a4%87%e6%95%b8%e6%93%9a%e5%ba%ab","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/183622\/","title":{"rendered":"\u4f7f\u7528C LINQ\u5be6\u73fe\u6578\u64da\u5eab\u53bb\u91cd\u7ba1\u7406 (c linq \u4e0d\u91cd\u8907\u6578\u64da\u5eab)"},"content":{"rendered":"<h1 id=\"%e4%bd%bf%e7%94%a8c-linq%e5%af%a6%e7%8f%be%e6%95%b8%e6%93%9a%e5%ba%ab%e5%8e%bb%e9%87%8d%e7%ae%a1%e7%90%86-EbUApqQxwP\">\u4f7f\u7528C LINQ\u5be6\u73fe\u6578\u64da\u5eab\u53bb\u91cd\u7ba1\u7406<\/h1>\n<p>\u5728\u7576\u4eca\u6578\u64da\u9a45\u52d5\u7684\u4e16\u754c\u4e2d\uff0c\u6578\u64da\u7684\u6e96\u78ba\u6027\u548c\u5b8c\u6574\u6027\u81f3\u95dc\u91cd\u8981\u3002\u91cd\u8907\u6578\u64da\u4e0d\u50c5\u6703\u6d6a\u8cbb\u5b58\u5132\u7a7a\u9593\uff0c\u9084\u53ef\u80fd\u5c0e\u81f4\u932f\u8aa4\u7684\u5206\u6790\u7d50\u679c\u548c\u6c7a\u7b56\u3002\u56e0\u6b64\uff0c\u6578\u64da\u5eab\u53bb\u91cd\u7ba1\u7406\u6210\u70ba\u4e86\u6578\u64da\u7ba1\u7406\u4e2d\u7684\u4e00\u500b\u91cd\u8981\u8ab2\u984c\u3002C#\u4e2d\u7684LINQ\uff08Language Integrated Query\uff09\u63d0\u4f9b\u4e86\u4e00\u7a2e\u7c21\u4fbf\u7684\u65b9\u6cd5\u4f86\u8655\u7406\u6578\u64da\uff0c\u5305\u62ec\u53bb\u91cd\u64cd\u4f5c\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u4f7f\u7528C LINQ\u4f86\u5be6\u73fe\u6578\u64da\u5eab\u7684\u53bb\u91cd\u7ba1\u7406\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%aflinq%ef%bc%9f-EbUApqQxwP\">\u4ec0\u9ebc\u662fLINQ\uff1f<\/h2>\n<p>LINQ\u662f\u4e00\u7a2e\u7528\u65bc\u67e5\u8a62\u6578\u64da\u7684\u8a9e\u8a00\u96c6\u6210\u6280\u8853\uff0c\u5141\u8a31\u958b\u767c\u8005\u4ee5\u66f4\u7c21\u6f54\u7684\u65b9\u5f0f\u5f9e\u5404\u7a2e\u6578\u64da\u6e90\uff08\u5982\u6578\u64da\u5eab\u3001XML\u6587\u4ef6\u3001\u96c6\u5408\u7b49\uff09\u4e2d\u6aa2\u7d22\u548c\u64cd\u4f5c\u6578\u64da\u3002LINQ\u7684\u8a9e\u6cd5\u7c21\u55ae\u6613\u61c2\uff0c\u4e26\u4e14\u80fd\u5920\u8207C#\u8a9e\u8a00\u7121\u7e2b\u96c6\u6210\uff0c\u4f7f\u5f97\u6578\u64da\u64cd\u4f5c\u8b8a\u5f97\u66f4\u52a0\u9ad8\u6548\u3002<\/p>\n<h2 id=\"%e7%82%ba%e4%bb%80%e9%ba%bc%e9%9c%80%e8%a6%81%e5%8e%bb%e9%87%8d%ef%bc%9f-EbUApqQxwP\">\u70ba\u4ec0\u9ebc\u9700\u8981\u53bb\u91cd\uff1f<\/h2>\n<p>\u5728\u6578\u64da\u5eab\u4e2d\uff0c\u91cd\u8907\u6578\u64da\u53ef\u80fd\u6703\u5c0e\u81f4\u591a\u7a2e\u554f\u984c\uff0c\u5305\u62ec\uff1a<\/p>\n<ul>\n<li>\u6578\u64da\u4e0d\u4e00\u81f4\u6027\uff1a\u91cd\u8907\u7684\u6578\u64da\u53ef\u80fd\u6703\u5c0e\u81f4\u4e0d\u540c\u7684\u6578\u64da\u4f86\u6e90\u7522\u751f\u77db\u76fe\u3002<\/li>\n<li>\u6027\u80fd\u554f\u984c\uff1a\u91cd\u8907\u6578\u64da\u6703\u589e\u52a0\u67e5\u8a62\u7684\u8ca0\u64d4\uff0c\u5f71\u97ff\u7cfb\u7d71\u6027\u80fd\u3002<\/li>\n<li>\u5b58\u5132\u6d6a\u8cbb\uff1a\u91cd\u8907\u6578\u64da\u4f54\u7528\u984d\u5916\u7684\u5b58\u5132\u7a7a\u9593\uff0c\u589e\u52a0\u4e86\u7ba1\u7406\u6210\u672c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%bd%bf%e7%94%a8c-linq%e9%80%b2%e8%a1%8c%e5%8e%bb%e9%87%8d%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%ad%a5%e9%a9%9f-EbUApqQxwP\">\u4f7f\u7528C LINQ\u9032\u884c\u53bb\u91cd\u7684\u57fa\u672c\u6b65\u9a5f<\/h2>\n<p>\u4f7f\u7528C LINQ\u9032\u884c\u6578\u64da\u53bb\u91cd\u7684\u904e\u7a0b\u901a\u5e38\u5305\u62ec\u4ee5\u4e0b\u5e7e\u500b\u6b65\u9a5f\uff1a<\/p>\n<h3 id=\"1-%e9%80%a3%e6%8e%a5%e5%88%b0%e6%95%b8%e6%93%9a%e5%ba%ab-EbUApqQxwP\">1. \u9023\u63a5\u5230\u6578\u64da\u5eab<\/h3>\n<p>\u9996\u5148\uff0c\u9700\u8981\u5efa\u7acb\u8207\u6578\u64da\u5eab\u7684\u9023\u63a5\u3002\u9019\u53ef\u4ee5\u901a\u904eEntity Framework\u6216ADO.NET\u4f86\u5be6\u73fe\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528Entity Framework\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>\nusing (var context = new YourDbContext())\n{\n    \/\/ \u6578\u64da\u5eab\u64cd\u4f5c\n}\n<\/code><\/pre>\n<h3 id=\"2-%e6%9f%a5%e8%a9%a2%e6%95%b8%e6%93%9a-EbUApqQxwP\">2. \u67e5\u8a62\u6578\u64da<\/h3>\n<p>\u63a5\u4e0b\u4f86\uff0c\u4f7f\u7528LINQ\u67e5\u8a62\u6578\u64da\u3002\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba\u201cUsers\u201d\u7684\u8868\uff0c\u6211\u5011\u5e0c\u671b\u53bb\u9664\u91cd\u8907\u7684\u7528\u6236\u540d\uff1a<\/p>\n<pre><code>\nvar users = context.Users.ToList();\n<\/code><\/pre>\n<h3 id=\"3-%e5%8e%bb%e9%87%8d%e6%93%8d%e4%bd%9c-EbUApqQxwP\">3. \u53bb\u91cd\u64cd\u4f5c<\/h3>\n<p>\u4f7f\u7528LINQ\u7684Distinct\u65b9\u6cd5\u4f86\u53bb\u9664\u91cd\u8907\u7684\u6578\u64da\u3002\u4ee5\u4e0b\u662f\u53bb\u91cd\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>\nvar distinctUsers = users.Select(u =&gt; u.Username).Distinct().ToList();\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6211\u5011\u9996\u5148\u9078\u64c7\u7528\u6236\u540d\uff0c\u7136\u5f8c\u4f7f\u7528Distinct\u65b9\u6cd5\u4f86\u7372\u53d6\u552f\u4e00\u7684\u7528\u6236\u540d\u5217\u8868\u3002<\/p>\n<h3 id=\"4-%e6%9b%b4%e6%96%b0%e6%95%b8%e6%93%9a%e5%ba%ab-EbUApqQxwP\">4. \u66f4\u65b0\u6578\u64da\u5eab<\/h3>\n<p>\u6700\u5f8c\uff0c\u5c07\u53bb\u91cd\u5f8c\u7684\u6578\u64da\u66f4\u65b0\u56de\u6578\u64da\u5eab\u3002\u9019\u53ef\u4ee5\u901a\u904e\u904d\u6b77distinctUsers\u4e26\u5c07\u5176\u63d2\u5165\u5230\u6578\u64da\u5eab\u4e2d\u4f86\u5be6\u73fe\uff1a<\/p>\n<pre><code>\nforeach (var username in distinctUsers)\n{\n    \/\/ \u6aa2\u67e5\u7528\u6236\u540d\u662f\u5426\u5df2\u5b58\u5728\n    if (!context.Users.Any(u =&gt; u.Username == username))\n    {\n        context.Users.Add(new User { Username = username });\n    }\n}\ncontext.SaveChanges();\n<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-EbUApqQxwP\">\u7e3d\u7d50<\/h2>\n<p>\u4f7f\u7528C LINQ\u9032\u884c\u6578\u64da\u5eab\u53bb\u91cd\u7ba1\u7406\u662f\u4e00\u500b\u9ad8\u6548\u4e14\u7c21\u55ae\u7684\u89e3\u6c7a\u65b9\u6848\u3002\u901a\u904eLINQ\u7684\u67e5\u8a62\u80fd\u529b\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u8f15\u9b06\u5730\u5f9e\u6578\u64da\u5eab\u4e2d\u6aa2\u7d22\u548c\u53bb\u9664\u91cd\u8907\u6578\u64da\uff0c\u5f9e\u800c\u63d0\u9ad8\u6578\u64da\u7684\u6e96\u78ba\u6027\u548c\u7cfb\u7d71\u6027\u80fd\u3002\u5c0d\u65bc\u9700\u8981\u8655\u7406\u5927\u91cf\u6578\u64da\u7684\u61c9\u7528\u7a0b\u5e8f\uff0c\u9019\u7a2e\u65b9\u6cd5\u5c24\u70ba\u91cd\u8981\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u53ef\u9760\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\u4f86\u652f\u6301\u60a8\u7684\u6578\u64da\u5eab\u7ba1\u7406\u9700\u6c42\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u5e6b\u52a9\u60a8\u8f15\u9b06\u7ba1\u7406\u548c\u512a\u5316\u60a8\u7684\u6578\u64da\u5eab\u74b0\u5883\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4f7f\u7528C LINQ\u6280\u8853\u9ad8\u6548\u5be6\u73fe\u6578\u64da\u5eab\u53bb\u91cd\u7ba1\u7406\uff0c\u78ba\u4fdd\u6578\u64da\u552f\u4e00\u6027\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u6548\u7387\u8207\u6e96\u78ba\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-183622","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/183622","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=183622"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/183622\/revisions"}],"predecessor-version":[{"id":183623,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/183622\/revisions\/183623"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=183622"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=183622"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=183622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}