{"id":2491,"date":"2013-03-08T12:40:13","date_gmt":"2013-03-08T12:40:13","guid":{"rendered":"http:\/\/enjoyasp.net\/?p=2491"},"modified":"2025-01-08T12:48:36","modified_gmt":"2025-01-08T04:48:36","slug":"linq%e5%9f%ba%e6%9c%ac%e6%93%8d%e4%bd%9c","status":"publish","type":"post","link":"https:\/\/enjoyasp.net\/index.php\/2013\/03\/08\/linq%e5%9f%ba%e6%9c%ac%e6%93%8d%e4%bd%9c\/","title":{"rendered":"linq\u57fa\u672c\u64cd\u4f5c"},"content":{"rendered":"

 <\/p>\n

\u57fa\u672c LINQ \u67e5\u8be2\u64cd\u4f5c<\/a><\/h1>\n

\u4e00\uff0clinq to datatable
\n1,\u67e5\u8be2\u6570\u91cf
\nusing System.Linq;<\/p>\n

\u00a0dt.AsEnumerable()<\/div>\n
\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 .Count(row => row.Field<string>(“Column-A”) == “Y”<\/div>\n
\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0|| row.Field<string>(“Column-A”) == “N”);
\nDataTable\u7684select\u53ea\u80fd\u7528\u4e00\u4e2a\u6761\u4ef6\u30022,top 1
\ndtExtOperate.AsEnumerable().First(dr => dr.Field<string>(\"RoleID\") == \"1101021\");
\nXML:<\/code><\/p>\n
return xdoc.Descendants(“Cache”).First(u => u.Attribute(“key”) != null && u.Attribute(“key”).Value == Key).Attribute(“value”).Value;<\/div>\n

3,<\/code><\/p>\n

\u5173\u952e\u5b57\u00a0var :<\/span><\/code><\/p>\n

\u3000\u3000\u3000\u3000<\/em>\u6307\u793a\u7f16\u8bd1\u5668\u6839\u636e\u521d\u59cb\u5316\u8bed\u53e5\u53f3\u4fa7\u7684\u8868\u8fbe\u5f0f\u63a8\u65ad\u53d8\u91cf\u7684\u7c7b\u578b\u3002 \u63a8\u65ad\u7c7b\u578b\u53ef\u4ee5\u662f\u5185\u7f6e\u7c7b\u578b\u3001\u533f\u540d\u7c7b\u578b\u3001\u7528\u6237\u5b9a\u4e49\u7c7b\u578b\u6216 .NET Framework \u7c7b\u5e93\u4e2d\u5b9a\u4e49\u7684\u7c7b\u578b\u3002\u8fd9\u6837\u6211\u4eec\u5c31\u53ef\u4ee5\u5728\u4e0a\u8ff0\u7684LINQ\u8868\u8fbe\u5f0f\u4e2d \u4f8b\u5982\u53ef\u7b80\u5199\u4e3a\uff1a var nums = from n in nums where .... orderby... select....<\/code><\/p>\n

4,linq\u5de5\u5177 http:\/\/www.linqpad.net\/<\/p>\n

5\uff0clinq\u5ef6\u8fdf\u52a0\u8f7d\uff0c\u5728\u7528\u7684\u65f6\u5019\u518d\u6267\u884c<\/p>\n

6\uff0c\u6392\u91cd<\/p>\n

 <\/p>\n

\/\/<\/span> \nIEnumerable<DataRow> rows = dt.AsEnumerbale();\n\/\/ \u53bb\u91cd\u590d<\/span>\nIEnumerable<\/span><DataRow> distinctRows = rows.Distinct(DataRowComparer.Default);<\/span><\/code><\/pre>\n<\/div>\n
7\uff0cselect many:\u9009\u62e9\u591a\u4e2a\u8f93\u51fa\u5217<\/p>\n
<\/pre>\n
string<\/span>[] fullNames = { \"<\/span>Anne Williams<\/span>\"<\/span>, \"<\/span>John Fred Smith<\/span>\"<\/span>, \"<\/span>Sue Green<\/span>\"<\/span> };\n            IEnumerable<string<\/span>> query = fullNames.SelectMany(name => name.Split());\n            foreach<\/span> (string<\/span> name in<\/span> query)\n                Console.Write(name + \"<\/span>|<\/span>\"<\/span>); \/\/<\/span> Anne|Williams|John|Fred|Smith|Sue|Green|\n\n\n<\/span><\/pre>\n
8,\u67e5\u8be2\u662f\u5426\u5b58\u5728
\ndtExtOperate.AsEnumerable().Any(dr => dr.Field<int>(“MenuID”) == MenuID)<\/p>\n
9.\u51fa\u5904\u00a0http:\/\/www.cnblogs.com\/jfzhu\/archive\/2013\/01\/01\/2841332.html<\/p>\n
\n
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\n
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\"image\"<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
  \u57fa\u672c LINQ \u67e5\u8be2\u64cd\u4f5c \u4e00\uff0clinq to datatable 1,\u67e5\u8be2\u6570\u91cf using Sy […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-2491","post","type-post","status-publish","format-standard","hentry","category-ado"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/posts\/2491","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/comments?post=2491"}],"version-history":[{"count":1,"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/posts\/2491\/revisions"}],"predecessor-version":[{"id":3333,"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/posts\/2491\/revisions\/3333"}],"wp:attachment":[{"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/media?parent=2491"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/categories?post=2491"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/enjoyasp.net\/index.php\/wp-json\/wp\/v2\/tags?post=2491"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}