{"id":186914,"date":"2024-11-11T09:53:23","date_gmt":"2024-11-11T01:53:23","guid":{"rendered":"https:\/\/server.hk\/cnblog\/186914\/"},"modified":"2024-11-11T09:53:24","modified_gmt":"2024-11-11T01:53:24","slug":"%e6%95%b8%e6%93%9a%e5%ba%ab%e5%91%bd%e4%bb%a4%ef%bc%9a%e5%8e%bb%e9%87%8d%e6%9f%a5%e8%a9%a2distinct-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%91%bd%e4%bb%a4-distinct","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/186914\/","title":{"rendered":"\u6578\u64da\u5eab\u547d\u4ee4\uff1a\u53bb\u91cd\u67e5\u8a62distinct (\u6578\u64da\u5eab\u547d\u4ee4 distinct)"},"content":{"rendered":"<h1 id=\"%e6%95%b8%e6%93%9a%e5%ba%ab%e5%91%bd%e4%bb%a4%ef%bc%9a%e5%8e%bb%e9%87%8d%e6%9f%a5%e8%a9%a2distinct-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%91%bd%e4%bb%a4-distinct-vcxrVKbaUM\">\u6578\u64da\u5eab\u547d\u4ee4\uff1a\u53bb\u91cd\u67e5\u8a62distinct (\u6578\u64da\u5eab\u547d\u4ee4 distinct)<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u6578\u64da\u7684\u91cd\u8907\u6027\u662f\u4e00\u500b\u5e38\u898b\u7684\u554f\u984c\u3002\u7576\u6211\u5011\u9700\u8981\u5f9e\u6578\u64da\u5eab\u4e2d\u63d0\u53d6\u552f\u4e00\u7684\u6578\u64da\u6642\uff0c<code>DISTINCT<\/code>\u547d\u4ee4\u4fbf\u6210\u70ba\u4e86\u4e00\u500b\u975e\u5e38\u6709\u7528\u7684\u5de5\u5177\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e<code>DISTINCT<\/code>\u547d\u4ee4\u7684\u7528\u6cd5\u3001\u539f\u7406\u53ca\u5176\u5728\u5be6\u969b\u61c9\u7528\u4e2d\u7684\u91cd\u8981\u6027\u3002<\/p>\n<h2 id=\"distinct%e5%91%bd%e4%bb%a4%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-vcxrVKbaUM\">DISTINCT\u547d\u4ee4\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n<p><code>DISTINCT<\/code>\u662f\u4e00\u500bSQL\u547d\u4ee4\uff0c\u7528\u65bc\u5f9e\u67e5\u8a62\u7d50\u679c\u4e2d\u53bb\u9664\u91cd\u8907\u7684\u6578\u64da\u884c\u3002\u7576\u6211\u5011\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528<code>DISTINCT<\/code>\u6642\uff0c\u6578\u64da\u5eab\u5c07\u53ea\u8fd4\u56de\u552f\u4e00\u7684\u6578\u64da\u884c\uff0c\u9019\u5c0d\u65bc\u6578\u64da\u5206\u6790\u548c\u5831\u544a\u751f\u6210\u975e\u5e38\u91cd\u8981\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8distinct%e7%9a%84%e5%9f%ba%e6%9c%ac%e8%aa%9e%e6%b3%95-vcxrVKbaUM\">\u4f7f\u7528DISTINCT\u7684\u57fa\u672c\u8a9e\u6cd5<\/h2>\n<p>\u4f7f\u7528<code>DISTINCT<\/code>\u547d\u4ee4\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SELECT DISTINCT column1, column2, ...\nFROM table_name;\n<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>column1, column2, ...<\/code>\u662f\u6211\u5011\u5e0c\u671b\u67e5\u8a62\u7684\u5217\u540d\uff0c\u800c<code>table_name<\/code>\u5247\u662f\u6578\u64da\u4f86\u6e90\u7684\u8868\u540d\u3002<\/p>\n<h2 id=\"distinct%e7%9a%84%e5%af%a6%e9%9a%9b%e6%87%89%e7%94%a8%e7%a4%ba%e4%be%8b-vcxrVKbaUM\">DISTINCT\u7684\u5be6\u969b\u61c9\u7528\u793a\u4f8b<\/h2>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba<code>customers<\/code>\u7684\u8868\uff0c\u8a72\u8868\u5305\u542b\u4ee5\u4e0b\u6578\u64da\uff1a<\/p>\n<pre><code>+----+----------+\n| ID | Country  |\n+----+----------+\n| 1  | USA      |\n| 2  | Canada   |\n| 3  | USA      |\n| 4  | Mexico    |\n| 5  | Canada   |\n+----+----------+\n<\/code><\/pre>\n<p>\u5982\u679c\u6211\u5011\u60f3\u8981\u67e5\u8a62\u6240\u6709\u7368\u7279\u7684\u570b\u5bb6\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0bSQL\u8a9e\u53e5\uff1a<\/p>\n<pre><code>SELECT DISTINCT Country\nFROM customers;\n<\/code><\/pre>\n<p>\u57f7\u884c\u4e0a\u8ff0\u67e5\u8a62\u5f8c\uff0c\u7d50\u679c\u5c07\u662f\uff1a<\/p>\n<pre><code>+----------+\n| Country  |\n+----------+\n| USA      |\n| Canada   |\n| Mexico    |\n+----------+\n<\/code><\/pre>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-vcxrVKbaUM\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528<code>DISTINCT<\/code>\u547d\u4ee4\u6642\uff0c\u6709\u5e7e\u9ede\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ul>\n<li><strong>\u6027\u80fd\u5f71\u97ff\uff1a<\/strong>\u4f7f\u7528<code>DISTINCT<\/code>\u53ef\u80fd\u6703\u5f71\u97ff\u67e5\u8a62\u6027\u80fd\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\u3002\u56e0\u70ba\u6578\u64da\u5eab\u9700\u8981\u984d\u5916\u7684\u8a08\u7b97\u4f86\u53bb\u9664\u91cd\u8907\u884c\u3002<\/li>\n<li><strong>\u591a\u5217\u67e5\u8a62\uff1a<\/strong>\u7576\u5728\u591a\u5217\u4e0a\u4f7f\u7528<code>DISTINCT<\/code>\u6642\uff0c\u53ea\u6709\u7576\u6240\u6709\u5217\u7684\u7d44\u5408\u90fd\u662f\u552f\u4e00\u7684\u6642\uff0c\u8a72\u884c\u624d\u6703\u88ab\u8fd4\u56de\u3002<\/li>\n<li><strong>NULL\u503c\uff1a<\/strong>\u5728\u4f7f\u7528<code>DISTINCT<\/code>\u6642\uff0cNULL\u503c\u4e5f\u6703\u88ab\u8996\u70ba\u4e00\u500b\u7368\u7279\u7684\u503c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-vcxrVKbaUM\">\u7d50\u8ad6<\/h2>\n<p>\u7e3d\u7d50\u4f86\u8aaa\uff0c<code>DISTINCT<\/code>\u547d\u4ee4\u5728\u6578\u64da\u5eab\u67e5\u8a62\u4e2d\u626e\u6f14\u8457\u91cd\u8981\u7684\u89d2\u8272\uff0c\u5e6b\u52a9\u7528\u6236\u7372\u53d6\u552f\u4e00\u7684\u6578\u64da\u884c\u3002\u7121\u8ad6\u662f\u5728\u6578\u64da\u5206\u6790\u9084\u662f\u5831\u544a\u751f\u6210\u4e2d\uff0c<code>DISTINCT<\/code>\u90fd\u80fd\u6709\u6548\u5730\u63d0\u9ad8\u6578\u64da\u7684\u53ef\u8b80\u6027\u548c\u6e96\u78ba\u6027\u3002\u5c0d\u65bc\u9700\u8981\u8655\u7406\u5927\u91cf\u6578\u64da\u7684\u4f01\u696d\u4f86\u8aaa\uff0c\u7406\u89e3\u548c\u6b63\u78ba\u4f7f\u7528<code>DISTINCT<\/code>\u547d\u4ee4\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u6216\u5176\u4ed6\u76f8\u95dc\u6280\u8853\u6709\u8208\u8da3\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4e86\u89e3\u66f4\u591a\u8cc7\u8a0a\u3002\u6211\u5011\u63d0\u4f9b\u5404\u7a2e<code><a href=\"https:\/\/server.hk\">VPS<\/a><\/code>\u89e3\u6c7a\u65b9\u6848\uff0c\u5e6b\u52a9\u60a8\u66f4\u597d\u5730\u7ba1\u7406\u548c\u904b\u7528\u60a8\u7684\u6578\u64da\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u6578\u64da\u5eab\u547d\u4ee4\u4e2d\u7684\u53bb\u91cd\u67e5\u8a62distinct\uff0c\u8f15\u9b06\u7372\u53d6\u552f\u4e00\u6578\u64da\uff0c\u63d0\u5347\u67e5\u8a62\u6548\u7387\uff0c\u512a\u5316\u6578\u64da\u7ba1\u7406\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-186914","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186914","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=186914"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186914\/revisions"}],"predecessor-version":[{"id":186915,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186914\/revisions\/186915"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=186914"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=186914"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=186914"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}