{"id":183620,"date":"2024-11-10T06:20:16","date_gmt":"2024-11-09T22:20:16","guid":{"rendered":"https:\/\/server.hk\/cnblog\/183620\/"},"modified":"2024-11-10T06:20:17","modified_gmt":"2024-11-09T22:20:17","slug":"%e4%bd%bf%e7%94%a8c-linq%e6%9f%a5%e8%a9%a2%e6%95%b8%e6%93%9a%e5%ba%ab%e9%83%a8%e5%88%86%e6%95%b8%e6%93%9a-c-linq%e6%9f%a5%e8%a9%a2%e4%b8%80%e9%83%a8%e5%88%86%e6%95%b8%e6%93%9a%e5%ba%ab","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/183620\/","title":{"rendered":"\u4f7f\u7528C LINQ\u67e5\u8a62\u6578\u64da\u5eab\u90e8\u5206\u6578\u64da (c linq\u67e5\u8a62\u4e00\u90e8\u5206\u6578\u64da\u5eab)"},"content":{"rendered":"<h1 id=\"%e4%bd%bf%e7%94%a8c-linq%e6%9f%a5%e8%a9%a2%e6%95%b8%e6%93%9a%e5%ba%ab%e9%83%a8%e5%88%86%e6%95%b8%e6%93%9a-HMSuFkjZks\">\u4f7f\u7528C# LINQ\u67e5\u8a62\u6578\u64da\u5eab\u90e8\u5206\u6578\u64da<\/h1>\n<p>\u5728\u73fe\u4ee3\u61c9\u7528\u7a0b\u5e8f\u958b\u767c\u4e2d\uff0c\u6578\u64da\u5eab\u67e5\u8a62\u662f\u4e0d\u53ef\u6216\u7f3a\u7684\u4e00\u90e8\u5206\u3002C#\u4e2d\u7684LINQ\uff08Language Integrated Query\uff09\u63d0\u4f9b\u4e86\u4e00\u7a2e\u7c21\u6f54\u800c\u5f37\u5927\u7684\u65b9\u5f0f\u4f86\u67e5\u8a62\u6578\u64da\u5eab\u4e2d\u7684\u6578\u64da\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u4f7f\u7528C# LINQ\u67e5\u8a62\u6578\u64da\u5eab\u7684\u90e8\u5206\u6578\u64da\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5be6\u7528\u7684\u793a\u4f8b\u548c\u4ee3\u78bc\u7247\u6bb5\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%aflinq%ef%bc%9f-HMSuFkjZks\">\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\u4f7f\u7528C#\u8a9e\u8a00\u7684\u8a9e\u6cd5\u4f86\u67e5\u8a62\u5404\u7a2e\u6578\u64da\u6e90\uff0c\u5305\u62ec\u6578\u64da\u5eab\u3001XML\u6587\u4ef6\u548c\u96c6\u5408\u7b49\u3002LINQ\u7684\u4e3b\u8981\u512a\u52e2\u5728\u65bc\u5176\u53ef\u8b80\u6027\u548c\u7c21\u6f54\u6027\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u7528\u66f4\u5c11\u7684\u4ee3\u78bc\u5be6\u73fe\u8907\u96dc\u7684\u67e5\u8a62\u3002<\/p>\n<h2 id=\"linq%e7%9a%84%e5%9f%ba%e6%9c%ac%e7%94%a8%e6%b3%95-HMSuFkjZks\">LINQ\u7684\u57fa\u672c\u7528\u6cd5<\/h2>\n<p>\u5728\u4f7f\u7528LINQ\u67e5\u8a62\u6578\u64da\u5eab\u4e4b\u524d\uff0c\u9996\u5148\u9700\u8981\u78ba\u4fdd\u5df2\u7d93\u5b89\u88dd\u4e86Entity Framework\u6216\u5176\u4ed6\u652f\u6301LINQ\u7684\u6578\u64da\u8a2a\u554f\u6280\u8853\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u793a\u4f8b\uff0c\u5c55\u793a\u5982\u4f55\u4f7f\u7528LINQ\u67e5\u8a62\u6578\u64da\u5eab\u4e2d\u7684\u90e8\u5206\u6578\u64da\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b%ef%bc%9a%e6%9f%a5%e8%a9%a2%e7%89%b9%e5%ae%9a%e6%a2%9d%e4%bb%b6%e7%9a%84%e6%95%b8%e6%93%9a-HMSuFkjZks\">\u793a\u4f8b\uff1a\u67e5\u8a62\u7279\u5b9a\u689d\u4ef6\u7684\u6578\u64da<\/h3>\n<pre><code>using System;\nusing System.Collections.Generic;\nusing System.Linq;\nusing System.Data.Entity;\n\npublic class Product\n{\n    public int Id { get; set; }\n    public string Name { get; set; }\n    public decimal Price { get; set; }\n}\n\npublic class ProductContext : DbContext\n{\n    public DbSet&lt;Product&gt; Products { get; set; }\n}\n\nclass Program\n{\n    static void Main()\n    {\n        using (var context = new ProductContext())\n        {\n            \/\/ \u67e5\u8a62\u50f9\u683c\u5927\u65bc100\u7684\u7522\u54c1\n            var expensiveProducts = from p in context.Products\n                                    where p.Price &gt; 100\n                                    select p;\n\n            foreach (var product in expensiveProducts)\n            {\n                Console.WriteLine($\"\u7522\u54c1\u540d\u7a31: {product.Name}, \u50f9\u683c: {product.Price}\");\n            }\n        }\n    }\n}\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u793a\u4f8b\u4e2d\uff0c\u6211\u5011\u5b9a\u7fa9\u4e86\u4e00\u500b\u540d\u70baProduct\u7684\u985e\uff0c\u4e26\u5275\u5efa\u4e86\u4e00\u500bProductContext\u4f86\u8a2a\u554f\u6578\u64da\u5eab\u3002\u7136\u5f8c\uff0c\u6211\u5011\u4f7f\u7528LINQ\u67e5\u8a62\u6240\u6709\u50f9\u683c\u5927\u65bc100\u7684\u7522\u54c1\uff0c\u4e26\u5c07\u5176\u8f38\u51fa\u5230\u63a7\u5236\u53f0\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8linq%e6%9f%a5%e8%a9%a2%e9%83%a8%e5%88%86%e6%95%b8%e6%93%9a-HMSuFkjZks\">\u4f7f\u7528LINQ\u67e5\u8a62\u90e8\u5206\u6578\u64da<\/h2>\n<p>\u6709\u6642\u5019\uff0c\u6211\u5011\u53ea\u9700\u8981\u67e5\u8a62\u6578\u64da\u5eab\u4e2d\u7684\u90e8\u5206\u6578\u64da\uff0c\u800c\u4e0d\u662f\u6574\u500b\u6578\u64da\u96c6\u3002\u9019\u53ef\u4ee5\u901a\u904e\u4f7f\u7528LINQ\u7684\u9078\u64c7\u5668\u4f86\u5be6\u73fe\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\uff0c\u5c55\u793a\u5982\u4f55\u67e5\u8a62\u7279\u5b9a\u5b57\u6bb5\u7684\u6578\u64da\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b%ef%bc%9a%e6%9f%a5%e8%a9%a2%e7%89%b9%e5%ae%9a%e5%ad%97%e6%ae%b5-HMSuFkjZks\">\u793a\u4f8b\uff1a\u67e5\u8a62\u7279\u5b9a\u5b57\u6bb5<\/h3>\n<pre><code>using (var context = new ProductContext())\n{\n    \/\/ \u53ea\u67e5\u8a62\u7522\u54c1\u540d\u7a31\u548c\u50f9\u683c\n    var productNamesAndPrices = from p in context.Products\n                                 select new { p.Name, p.Price };\n\n    foreach (var item in productNamesAndPrices)\n    {\n        Console.WriteLine($\"\u7522\u54c1\u540d\u7a31: {item.Name}, \u50f9\u683c: {item.Price}\");\n    }\n}\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u793a\u4f8b\u4e2d\uff0c\u6211\u5011\u4f7f\u7528\u4e86\u533f\u540d\u985e\u578b\u4f86\u53ea\u9078\u64c7\u7522\u54c1\u7684\u540d\u7a31\u548c\u50f9\u683c\uff0c\u9019\u6a23\u53ef\u4ee5\u6e1b\u5c11\u5f9e\u6578\u64da\u5eab\u4e2d\u6aa2\u7d22\u7684\u6578\u64da\u91cf\uff0c\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/p>\n<h2 id=\"linq%e7%9a%84%e5%84%aa%e5%8b%a2-HMSuFkjZks\">LINQ\u7684\u512a\u52e2<\/h2>\n<ul>\n<li><strong>\u53ef\u8b80\u6027\uff1a<\/strong>LINQ\u7684\u8a9e\u6cd5\u63a5\u8fd1\u81ea\u7136\u8a9e\u8a00\uff0c\u4f7f\u5f97\u67e5\u8a62\u66f4\u6613\u65bc\u7406\u89e3\u3002<\/li>\n<li><strong>\u5f37\u5927\u7684\u529f\u80fd\uff1a<\/strong>LINQ\u652f\u6301\u591a\u7a2e\u67e5\u8a62\u64cd\u4f5c\uff0c\u5982\u904e\u6ffe\u3001\u6392\u5e8f\u548c\u5206\u7d44\u7b49\u3002<\/li>\n<li><strong>\u985e\u578b\u5b89\u5168\uff1a<\/strong>LINQ\u5728\u7de8\u8b6f\u6642\u9032\u884c\u985e\u578b\u6aa2\u67e5\uff0c\u6e1b\u5c11\u4e86\u904b\u884c\u6642\u932f\u8aa4\u7684\u53ef\u80fd\u6027\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-HMSuFkjZks\">\u7e3d\u7d50<\/h2>\n<p>\u4f7f\u7528C# LINQ\u67e5\u8a62\u6578\u64da\u5eab\u90e8\u5206\u6578\u64da\u662f\u4e00\u7a2e\u9ad8\u6548\u4e14\u7c21\u55ae\u7684\u65b9\u6cd5\u3002\u901a\u904eLINQ\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u8f15\u9b06\u5730\u5f9e\u6578\u64da\u5eab\u4e2d\u6aa2\u7d22\u6240\u9700\u7684\u4fe1\u606f\uff0c\u4e26\u4e14\u80fd\u5920\u4ee5\u53ef\u8b80\u6027\u9ad8\u7684\u65b9\u5f0f\u7de8\u5beb\u67e5\u8a62\u4ee3\u78bc\u3002\u7121\u8ad6\u662f\u67e5\u8a62\u6574\u500b\u6578\u64da\u96c6\u9084\u662f\u90e8\u5206\u6578\u64da\uff0cLINQ\u90fd\u63d0\u4f9b\u4e86\u9748\u6d3b\u7684\u89e3\u6c7a\u65b9\u6848\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684\u6578\u64da\u5b58\u5132\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u4f86\u6258\u7ba1\u60a8\u7684\u61c9\u7528\u7a0b\u5e8f\uff0c\u9019\u5c07\u70ba\u60a8\u7684\u958b\u767c\u5de5\u4f5c\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4f7f\u7528C# LINQ\u8f15\u9b06\u67e5\u8a62\u6578\u64da\u5eab\u4e2d\u7684\u90e8\u5206\u6578\u64da\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u6548\u7387\uff0c\u7c21\u5316\u958b\u767c\u6d41\u7a0b\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-183620","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/183620","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=183620"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/183620\/revisions"}],"predecessor-version":[{"id":183621,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/183620\/revisions\/183621"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=183620"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=183620"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=183620"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}