{"id":116,"date":"2012-03-31T08:32:19","date_gmt":"2012-03-31T08:32:19","guid":{"rendered":"http:\/\/www.shuran.cn\/?p=116"},"modified":"2012-03-31T08:32:19","modified_gmt":"2012-03-31T08:32:19","slug":"select-%e5%8e%bb%e9%99%a4%e9%87%8d%e5%a4%8d%e7%9a%84%e5%85%b3%e9%94%ae%e5%ad%97%e7%94%a8%e6%b3%95","status":"publish","type":"post","link":"https:\/\/www.shuran.cn\/?p=116","title":{"rendered":"select \u53bb\u9664\u91cd\u590d\u7684\u5173\u952e\u5b57\u7528\u6cd5"},"content":{"rendered":"

\u8f6c\u6765\u7684\u3002\u8c22\u8c22\u4f5c\u8005\u3002<\/h2>\n

\u7528\u6cd5<\/p>\n

select\u00a0*,\u00a0count(distinct\u00a0name)\u00a0from\u00a0table\u00a0group\u00a0by\u00a0name<\/p>\n

\u4e0b\u9762\u4e3a\u4f5c\u8005\u539f\u6587<\/h2>\n

Select \u4e2dDISTINCT\u5173\u952e\u5b57\u7684\u7528\u6cd5?(\u8f6c)<\/a><\/h2>\n

\u5728\u4f7f\u7528mysql\u65f6\uff0c\u6709\u65f6\u9700\u8981\u67e5\u8be2\u51fa\u67d0\u4e2a\u5b57\u6bb5\u4e0d\u91cd\u590d\u7684\u8bb0\u5f55\uff0c\u867d\u7136mysql\u63d0\u4f9b\u6709distinct\u8fd9\u4e2a\u5173\u952e\u5b57\u6765\u8fc7\u6ee4\u6389\u591a\u4f59\u7684\u91cd\u590d\u8bb0\u5f55\u53ea\u4fdd\u7559\u4e00 \u6761\uff0c\u4f46\u5f80\u5f80\u53ea\u7528\u5b83\u6765\u8fd4\u56de\u4e0d\u91cd\u590d\u8bb0\u5f55\u7684\u6761\u6570\uff0c\u800c\u4e0d\u662f\u7528\u5b83\u6765\u8fd4\u56de\u4e0d\u91cd\u8bb0\u5f55\u7684\u6240\u6709\u503c\u3002\u5176\u539f\u56e0\u662fdistinct\u53ea\u80fd\u8fd4\u56de\u5b83\u7684\u76ee\u6807\u5b57\u6bb5\uff0c\u800c\u65e0\u6cd5\u8fd4\u56de\u5176\u5b83\u5b57\u6bb5\uff0c\u8fd9\u4e2a \u95ee\u9898\u8ba9\u6211\u56f0\u6270\u4e86\u5f88\u4e45\uff0c\u7528distinct\u4e0d\u80fd\u89e3\u51b3\u7684\u8bdd\uff0c\u6211\u53ea\u6709\u7528\u4e8c\u91cd\u5faa\u73af\u67e5\u8be2\u6765\u89e3\u51b3\uff0c\u800c\u8fd9\u6837\u5bf9\u4e8e\u4e00\u4e2a\u6570\u636e\u91cf\u975e\u5e38\u5927\u7684\u7ad9\u6765\u8bf4\uff0c\u65e0\u7591\u662f\u4f1a\u76f4\u63a5\u5f71\u54cd\u5230\u6548\u7387\u7684\u3002\u6240 \u4ee5\u6211\u82b1\u4e86\u5f88\u591a\u65f6\u95f4\u6765\u7814\u7a76\u8fd9\u4e2a\u95ee\u9898\uff0c\u7f51\u4e0a\u4e5f\u67e5\u4e0d\u5230\u89e3\u51b3\u65b9\u6848\uff0c\u671f\u95f4\u628a\u5bb9\u5bb9\u62c9\u6765\u5e2e\u5fd9\uff0c\u7ed3\u679c\u662f\u6211\u4eec\u4e24\u4eba\u90fd\u90c1\u95f7\u4e86\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002<\/p>\n

\u4e0b\u9762\u5148\u6765\u770b\u770b\u4f8b\u5b50\uff1a<\/p>\n

\u00a0\u00a0\u00a0\u00a0table
\nid\u00a0name
\n1\u00a0a
\n2\u00a0b
\n3\u00a0c
\n4\u00a0c
\n5\u00a0b<\/p>\n

\u5e93\u7ed3\u6784\u5927\u6982\u8fd9\u6837\uff0c\u8fd9\u53ea\u662f\u4e00\u4e2a\u7b80\u5355\u7684\u4f8b\u5b50\uff0c\u5b9e\u9645\u60c5\u51b5\u4f1a\u590d\u6742\u5f97\u591a\u3002<\/p>\n

\u6bd4\u5982\u6211\u60f3\u7528\u4e00\u6761\u8bed\u53e5\u67e5\u8be2\u5f97\u5230name\u4e0d\u91cd\u590d\u7684\u6240\u6709\u6570\u636e\uff0c\u90a3\u5c31\u5fc5\u987b\u4f7f\u7528distinct\u53bb\u6389\u591a\u4f59\u7684\u91cd\u590d\u8bb0\u5f55\u3002<\/p>\n

select\u00a0distinct\u00a0name\u00a0from\u00a0table
\n\u5f97\u5230\u7684\u7ed3\u679c\u662f:<\/p>\n

\u00a0\u00a0name
\na
\nb
\nc<\/p>\n

\u597d\u50cf\u8fbe\u5230\u6548\u679c\u4e86\uff0c\u53ef\u662f\uff0c\u6211\u60f3\u8981\u5f97\u5230\u7684\u662fid\u503c\u5462\uff1f\u6539\u4e00\u4e0b\u67e5\u8be2\u8bed\u53e5\u5427:<\/p>\n

select\u00a0distinct\u00a0name,\u00a0id\u00a0from\u00a0table<\/p>\n

\u7ed3\u679c\u4f1a\u662f:<\/p>\n

\u00a0\u00a0id\u00a0name
\n1\u00a0a
\n2\u00a0b
\n3\u00a0c
\n4\u00a0c
\n5\u00a0b<\/p>\n

distinct\u600e\u4e48\u6ca1\u8d77\u4f5c\u7528\uff1f\u4f5c\u7528\u662f\u8d77\u4e86\u7684\uff0c\u4e0d\u8fc7\u4ed6\u540c\u65f6\u4f5c\u7528\u4e86\u4e24\u4e2a\u5b57\u6bb5\uff0c\u4e5f\u5c31\u662f\u5fc5\u987b\u5f97id\u4e0ename\u90fd\u76f8\u540c\u7684\u624d\u4f1a\u88ab\u6392\u9664\u3002\u3002\u3002\u3002\u3002\u3002\u3002<\/p>\n

\u6211\u4eec\u518d\u6539\u6539\u67e5\u8be2\u8bed\u53e5:<\/p>\n

select\u00a0id,\u00a0distinct\u00a0name\u00a0from\u00a0table<\/p>\n

\u5f88\u9057\u61be\uff0c\u9664\u4e86\u9519\u8bef\u4fe1\u606f\u4f60\u4ec0\u4e48\u4e5f\u5f97\u4e0d\u5230\uff0cdistinct\u5fc5\u987b\u653e\u5728\u5f00\u5934\u3002\u96be\u5230\u4e0d\u80fd\u628adistinct\u653e\u5230where\u6761\u4ef6\u91cc\uff1f\u80fd\uff0c\u7167\u6837\u62a5 \u9519\u3002\u3002\u3002\u3002\u3002\u3002\u3002<\/p>\n

\u5f88\u9ebb\u70e6\u5427\uff1f\u786e\u5b9e\uff0c\u8d39\u5c3d\u5fc3\u601d\u90fd\u6ca1\u80fd\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\u3002\u6ca1\u529e\u6cd5\uff0c\u7ee7\u7eed\u627e\u4eba\u95ee\u3002<\/p>\n

\u62c9\u4f4f\u516c\u53f8\u91cc\u4e00JAVA\u7a0b\u5e8f\u5458\uff0c\u4ed6\u7ed9\u6211\u6f14\u793a\u4e86oracle\u91cc\u4f7f\u7528distinct\u4e4b\u540e\uff0c\u4e5f\u6ca1\u627e\u5230mysql\u91cc\u7684\u89e3\u51b3\u65b9\u6848\uff0c\u6700\u540e\u4e0b\u73ed\u4e4b\u524d\u4ed6\u5efa\u8bae\u6211\u8bd5\u8bd5 group\u00a0by\u3002<\/p>\n

\u8bd5\u4e86\u534a\u5929\uff0c\u4e5f\u4e0d\u884c\uff0c\u6700\u540e\u5728mysql\u624b\u518c\u91cc\u627e\u5230\u4e00\u4e2a\u7528\u6cd5\uff0c\u7528group_concat(distinct\u00a0name)\u914d\u5408 group\u00a0by\u00a0name\u5b9e\u73b0\u4e86\u6211\u6240\u9700\u8981\u7684\u529f\u80fd\uff0c\u5174\u594b\uff0c\u5929\u4f51\u6211\u4e5f\uff0c\u8d76\u5feb\u8bd5\u8bd5\u3002<\/p>\n

\u62a5\u9519\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u90c1\u95f7\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u8fdemysql\u624b\u518c\u4e5f\u8ddf\u6211\u8fc7\u4e0d\u53bb\uff0c\u5148\u7ed9\u4e86\u6211\u5e0c\u671b\uff0c\u7136\u540e\u53c8\u628a\u6211\u63a8\u5411\u5931\u671b\uff0c\u597d\u72e0\u54ea\u3002\u3002\u3002\u3002<\/p>\n

\u518d\u4ed4\u7ec6\u4e00\u67e5\uff0cgroup_concat\u51fd\u6570\u662f4.1\u652f\u6301\uff0c\u6655\uff0c\u62114.0\u7684\u3002\u6ca1\u529e\u6cd5\uff0c\u5347\u7ea7\uff0c\u5347\u5b8c\u7ea7\u4e00\u8bd5\uff0c\u6210\u529f\u3002\u3002\u3002\u3002\u3002\u3002<\/p>\n

\u7ec8\u4e8e\u641e\u5b9a\u4e86\uff0c\u4e0d\u8fc7\u8fd9\u6837\u4e00\u6765\uff0c\u53c8\u5fc5\u987b\u8981\u6c42\u5ba2\u6237\u4e5f\u5347\u7ea7\u4e86\u3002<\/p>\n

\u7a81\u7136\u7075\u673a\u4e00\u95ea\uff0c\u65e2\u7136\u53ef\u4ee5\u4f7f\u7528group_concat\u51fd\u6570\uff0c\u90a3\u5176\u5b83\u51fd\u6570\u80fd\u884c\u5417\uff1f<\/p>\n

\u8d76\u7d27\u7528count\u51fd\u6570\u4e00\u8bd5\uff0c\u6210\u529f\uff0c\u6211\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u60f3\u54ed\u554a\uff0c\u8d39\u4e86\u8fd9\u4e48\u591a\u5de5\u592b\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u539f\u6765\u5c31\u8fd9\u4e48\u7b80\u5355\u3002\u3002\u3002\u3002\u3002\u3002<\/p>\n

\u73b0\u5728\u5c06\u5b8c\u6574\u8bed\u53e5\u653e\u51fa:<\/p>\n

select\u00a0*,\u00a0count(distinct\u00a0name)\u00a0from\u00a0table\u00a0group\u00a0by\u00a0name<\/p>\n

\u7ed3\u679c:<\/p>\n

\u00a0\u00a0id\u00a0name\u00a0count(distinct\u00a0name)
\n1\u00a0a\u00a01
\n2\u00a0b\u00a01
\n3\u00a0c\u00a01<\/p>\n

\u6700\u540e\u4e00\u9879\u662f\u591a\u4f59\u7684\uff0c\u4e0d\u7528\u7ba1\u5c31\u884c\u4e86\uff0c\u76ee\u7684\u8fbe\u5230\u3002\u3002\u3002\u3002\u3002<\/p>\n

\u5509\uff0c\u539f\u6765mysql\u8fd9\u4e48\u7b28\uff0c\u8f7b\u8f7b\u4e00\u4e0b\u5c31\u628a\u4ed6\u9a97\u8fc7\u53bb\u4e86\uff0c\u90c1\u95f7\u4e5f\u5c31\u6211\u5427\uff08\u5bf9\u4e86\uff0c\u8fd8\u6709\u5bb9\u5bb9\u90a3\u5bb6\u4f19\uff09\uff0c\u73b0\u5728\u62ff\u51fa\u6765\u5e0c\u671b\u5927\u5bb6\u4e0d\u8981\u88ab\u8fd9\u95ee\u9898\u6298\u817e\u3002<\/p>\n

\u54e6\uff0c\u5bf9\uff0c\u518d\u987a\u4fbf\u8bf4\u4e00\u53e5\uff0cgroup\u00a0by\u00a0\u5fc5\u987b\u653e\u5728\u00a0order\u00a0by\u00a0\u548c\u00a0limit\u4e4b\u524d\uff0c\u4e0d\u7136\u4f1a\u62a5\u9519\uff0c\u5dee\u4e0d\u591a\u4e86\uff0c\u53d1\u7ed9\u5bb9\u5bb9\u653e\u7f51\u7ad9\u4e0a\u53bb\uff0c\u6211\u7ee7\u7eed\u5fd9 \u788c\u3002\u3002\u3002\u3002\u3002\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

\u8f6c\u6765\u7684\u3002\u8c22\u8c22\u4f5c\u8005\u3002 \u7528\u6cd5 select\u00a0*,\u00a0count(distinct\u00a0name)\u00a0from\u00a0table\u00a0\u2026 Read More »<\/a><\/span><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-116","post","type-post","status-publish","format-standard","hentry","category-php"],"_links":{"self":[{"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/posts\/116","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=116"}],"version-history":[{"count":2,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/posts\/116\/revisions"}],"predecessor-version":[{"id":124,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/posts\/116\/revisions\/124"}],"wp:attachment":[{"href":"https:\/\/www.shuran.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=116"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=116"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=116"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}