{"id":1777,"date":"2023-12-05T15:55:35","date_gmt":"2023-12-05T07:55:35","guid":{"rendered":"https:\/\/itoau.com\/?p=1777"},"modified":"2023-12-05T16:00:36","modified_gmt":"2023-12-05T08:00:36","slug":"sql%e5%ad%97%e6%ae%b5%e9%87%8d%e5%a4%8d%e5%80%bc%e7%9a%84%e6%9f%a5%e8%af%a2%e4%b8%8e%e7%ad%9b%e9%80%89","status":"publish","type":"post","link":"https:\/\/itoau.com\/?p=1777","title":{"rendered":"SQL\u5b57\u6bb5\u91cd\u590d\u503c\u7684\u67e5\u8be2\u4e0e\u7b5b\u9009"},"content":{"rendered":"<p>SQL\u5b57\u6bb5\u91cd\u590d\u503c\u7684\u67e5\u8be2\u4e0e\u7b5b\u9009<\/p>\n<p>1\u3001\u8981\u67e5\u8be2\u6307\u5b9a\u5b57\u6bb5\u6709\u91cd\u590d\u503c\u7684\u8bb0\u5f55<\/p>\n<p><span style=\"color: #ff0000;\">select fieldname, count(fieldname) as ccount from tablename group by fieldname having(fieldname) &gt; 1<\/span><\/p>\n<p>2\u3001\u8981\u67e5\u8be2\u8fc7\u8651\u6307\u5b9a\u5b57\u6bb5\u91cd\u590d\u503c\u7684\u6240\u6709\u8bb0\u5f55<\/p>\n<p><span style=\"color: #ff0000;\">select distinct fieldname from tablename<\/span><\/p>\n<p>\u5b9e\u4f8b\uff1a<\/p>\n<p>\u5728\u4ee5\u4e0b\u6570\u636e\u8868\u4e2d\u6267\u884c\u4e0a\u8ff0\u4e24\u79cd\u64cd\u4f5c<\/p>\n<p>1\u3001\u7b5b\u9009\u51fa\u6709\u91cd\u590d\u7684\u6570\u636e<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-1778\" src=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-30-01.jpg\" alt=\"\" width=\"408\" height=\"167\" srcset=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-30-01.jpg 408w, https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-30-01-300x123.jpg 300w\" sizes=\"auto, (max-width: 408px) 100vw, 408px\" \/><\/p>\n<p>select recval,count(recval) as ccount from rectable group by recval<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-1779\" src=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-32-27.jpg\" alt=\"\" width=\"689\" height=\"254\" srcset=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-32-27.jpg 689w, https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-32-27-300x111.jpg 300w\" sizes=\"auto, (max-width: 689px) 100vw, 689px\" \/><\/p>\n<p>\u8fdb\u4e00\u6b65\u7528having\u7b5b\u9009\u51fa\u6709\u91cd\u590d\u7684\u8bb0\u5f55<\/p>\n<p>select recval,count(recval) as ccount from rectable group by recval having count(recval)&gt;1<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-1780\" src=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-34-27.jpg\" alt=\"\" width=\"875\" height=\"152\" srcset=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-34-27.jpg 875w, https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-34-27-300x52.jpg 300w, https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-34-27-768x133.jpg 768w\" sizes=\"auto, (max-width: 875px) 100vw, 875px\" \/><\/p>\n<p>\u7528\u8fd9\u79cd\u65b9\u5f0f\u5f88\u5bb9\u6613\u5c31\u627e\u5230\u91cd\u590d\u7684\u8bb0\u5f55\uff0c\u4fbf\u4e8e\u8fdb\u884c\u6570\u636e\u5904\u7406\u3002<\/p>\n<p>2\u3001\u8fc7\u8651\u6389\u91cd\u590d\u6570\u636e<\/p>\n<p>select distinct recval from rectable<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-1783\" src=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-53-40.jpg\" alt=\"\" width=\"444\" height=\"253\" srcset=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-53-40.jpg 444w, https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-53-40-300x171.jpg 300w\" sizes=\"auto, (max-width: 444px) 100vw, 444px\" \/><\/p>\n<p>\u8fd9\u91cc\u9700\u6ce8\u610fdistinct\u53ef\u4ee5\u5bf9\u591a\u5b57\u6bb5\u91cd\u590d\u7b5b\u9009\uff0c\u4f46\u4f1a\u4ea7\u751f\u65e0\u91cd\u590d\u5b57\u6bb5\u5bf9\u6709\u91cd\u590d\u5b57\u6bb5\u7684\u5ffd\u7565\uff0c\u5373\u5728\u591a\u5b57\u6bb5\u4e2d\uff0c\u53ea\u8981\u6709\u672a\u91cd\u590d\u8bb0\u5f55\uff0c\u90fd\u4f1a\u8fd4\u56de\u7ed3\u679c\u3002<\/p>\n<p>\u5728\u6b64\u4f8b\u5b50\u4e2d\uff0c\u540c\u65f6\u5bf9recval\u3001recno\u4e24\u4e2a\u5b57\u6bb5\u8fdb\u884c\u91cd\u590d\u8fc7\u6ee4\uff0c\u867d\u7136recval\u6709\u91cd\u590d\u8bb0\u5f55\uff0c\u4f46\u7531\u4e8erecno\u5b57\u6bb5\u6ca1\u6709\u91cd\u590d\u8bb0\u5f55\uff0c\u6240\u4ee5\u67e5\u8be2\u7ed3\u679c\u5c06recno\u4e2d\u672a\u91cd\u590d\u7684\u5168\u90e8\u8fd4\u56de\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-1782\" src=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-42-45.jpg\" alt=\"\" width=\"471\" height=\"287\" srcset=\"https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-42-45.jpg 471w, https:\/\/itoau.com\/wp-content\/uploads\/2023\/12\/Snipaste_2023-12-05_15-42-45-300x183.jpg 300w\" sizes=\"auto, (max-width: 471px) 100vw, 471px\" \/><\/p>\n<p>\u6240\u4ee5\u6839\u636e\u4ee5\u4e0a\u7b80\u5355\u6d4b\u8bd5\uff0cdistinct\u66f4\u591a\u5730\u5e94\u7528\u4e8e\u5355\u5b57\u6bb5\u91cd\u590d\u8fc7\u6ee4\u67e5\u8be2\u3002<\/p>\n<p>\u5728\u5b9e\u9645\u4f7f\u7528\u4e2d\uff0c\u7b2c\u4e00\u79cd\u8bed\u53e5\u66f4\u4e3a\u5e38\u7528\uff0c\u56e0\u4e3a\u91cd\u590d\u8bb0\u5f55\u603b\u662f\u8981\u91cd\u70b9\u67e5\u627e\u7684\u76ee\u6807\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>SQL\u5b57\u6bb5\u91cd\u590d\u503c\u7684\u67e5\u8be2\u4e0e\u7b5b\u9009 1\u3001\u8981\u67e5\u8be2\u6307\u5b9a\u5b57\u6bb5\u6709\u91cd\u590d\u503c\u7684\u8bb0\u5f55 select fieldname, count [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"default","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center 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center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[44],"tags":[],"class_list":["post-1777","post","type-post","status-publish","format-standard","hentry","category-sql"],"_links":{"self":[{"href":"https:\/\/itoau.com\/index.php?rest_route=\/wp\/v2\/posts\/1777","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itoau.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itoau.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itoau.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itoau.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1777"}],"version-history":[{"count":3,"href":"https:\/\/itoau.com\/index.php?rest_route=\/wp\/v2\/posts\/1777\/revisions"}],"predecessor-version":[{"id":1786,"href":"https:\/\/itoau.com\/index.php?rest_route=\/wp\/v2\/posts\/1777\/revisions\/1786"}],"wp:attachment":[{"href":"https:\/\/itoau.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1777"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itoau.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1777"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itoau.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1777"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}