{"id":6701,"date":"2024-11-14T11:26:42","date_gmt":"2024-11-14T03:26:42","guid":{"rendered":"https:\/\/fwq.ai\/blog\/6701\/"},"modified":"2024-11-14T11:26:42","modified_gmt":"2024-11-14T03:26:42","slug":"mysql%e4%bc%aa%e8%a1%a8dual%e6%9c%89%e4%bb%80%e4%b9%88%e4%bd%9c%e7%94%a8%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/6701\/","title":{"rendered":"MySQL\u4f2a\u8868dual\u6709\u4ec0\u4e48\u4f5c\u7528\uff1f"},"content":{"rendered":"

\"MySQL\u4f2a\u8868dual\u6709\u4ec0\u4e48\u4f5c\u7528\uff1f\u63d2\u56fe\"<\/p>\n

\u4e2d\u7684\u4f2a\u8868 dual<\/strong><\/p>\n

\u4f7f\u7528\u4f2a\u8868 dual \u53ef\u4ee5\u4ece\u4e00\u4e2a\u4e0d\u5305\u542b\u4efb\u4f55\u771f\u5b9e\u6570\u636e\u7684\u865a\u62df\u8868\u4e2d\u68c0\u7d22\u6570\u636e\u3002\u5728 mysql \u4e2d\uff0cdual \u4f2a\u8868\u4e0e from \u5b50\u53e5\u4e2d\u4e0d\u5305\u542b\u4efb\u4f55\u8868\u7684\u67e5\u8be2\u5177\u6709\u76f8\u540c\u7684\u6548\u679c\u3002<\/p>\n

\u67e5\u8be2<\/strong><\/p>\n

\u63d0\u4f9b\u7684\u4e24\u4e2a\u67e5\u8be2\uff1a<\/p>\n

select 6+6 from dual;\nselect 6+6;<\/pre>\n
 \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
\u4ea7\u751f\u76f8\u540c\u7684\u7ed3\u679c\uff0812\uff09\uff0c\u56e0\u4e3a mysql \u5728\u4e0d\u4f7f\u7528 from \u5b50\u53e5\u7684\u60c5\u51b5\u4e0b\u76f4\u63a5\u4ece\u4f2a\u8868 dual \u4e2d\u68c0\u7d22\u6570\u636e\u3002<\/p>\n
\u4f2a\u8868\u7684\u7528\u6cd5<\/strong><\/p>\n
\u4f2a\u8868 dual \u5e38\u7528\u4e8e\u4ee5\u4e0b\u573a\u666f\uff1a<\/p>\n
    \n
  •  \u521d\u59cb\u5316\u5e8f\u5217\u548c\u6807\u8bc6\u5217\uff1a<\/strong>\u53ef\u4ee5\u4f7f\u7528 dual \u8868\u6765\u83b7\u53d6\u5e8f\u5217\u503c\u7684\u4e0b\u4e00\u4e2a\u503c\uff0c\u6216\u521d\u59cb\u5316\u6807\u8bc6\u5217\u7684\u503c\u3002<\/li>\n
  •  \u9a8c\u8bc1\u67e5\u8be2\u8bed\u6cd5\uff1a<\/strong>\u4ece dual \u8868\u4e2d\u68c0\u7d22\u6570\u636e\u53ef\u4ee5\u6d4b\u8bd5\u67e5\u8be2\u7684\u8bed\u6cd5\u662f\u5426\u6b63\u786e\uff0c\u800c\u65e0\u9700\u4f7f\u7528\u5b9e\u9645\u7684\u8868\u6570\u636e\u3002<\/li>\n
  •  \u63d0\u4f9b\u9ed8\u8ba4\u503c\uff1a<\/strong>\u5982\u679c\u5728\u67d0\u4e2a\u67e5\u8be2\u4e2d\u9700\u8981\u4e00\u4e2a\u9ed8\u8ba4\u503c\uff0c\u53ef\u4ee5\u4f7f\u7528 dual \u8868\u6765\u63d0\u4f9b\u8fd9\u4e2a\u503c\u3002<\/li>\n
  •  \u751f\u6210\u6d4b\u8bd5\u6570\u636e\uff1a<\/strong>\u53ef\u4ee5\u4f7f\u7528 dual \u8868\u6765\u751f\u6210\u4e00\u7ec4\u6d4b\u8bd5\u6570\u636e\uff0c\u4f8b\u5982\u7528\u4e8e\u6d4b\u8bd5\u51fd\u6570\u6216\u5b58\u50a8\u8fc7\u7a0b\u3002<\/li>\n<\/ul>\n
    \u4ee5\u4e0a\u5c31\u662fMySQL\u4f2a\u8868dual\u6709\u4ec0\u4e48\u4f5c\u7528\uff1f\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"
    \u4e2d\u7684\u4f2a\u8868 dual \u4f7f\u7528\u4f2a\u8868 dual \u53ef\u4ee5\u4ece\u4e00\u4e2a\u4e0d\u5305\u542b\u4efb\u4f55\u771f\u5b9e\u6570\u636e\u7684\u865a\u62df\u8868\u4e2d\u68c0\u7d22\u6570\u636e\u3002\u5728 mysql \u4e2d\uff0cdual \u4f2a\u8868\u4e0e from \u5b50\u53e5\u4e2d\u4e0d\u5305\u542b\u4efb\u4f55\u8868\u7684\u67e5\u8be2\u5177\u6709\u76f8\u540c\u7684\u6548\u679c\u3002 \u67e5\u8be2 \u63d0\u4f9b\u7684\u4e24\u4e2a\u67e5\u8be2\uff1a select 6+6 from dual; select 6+6; \u767b\u5f55\u540e\u590d\u5236 \u4ea7\u751f\u76f8\u540c\u7684\u7ed3\u679c\uff0812\uff09\uff0c\u56e0\u4e3a mysql \u5728\u4e0d\u4f7f\u7528 from \u5b50\u53e5\u7684\u60c5\u51b5\u4e0b\u76f4\u63a5\u4ece\u4f2a\u8868 dual \u4e2d\u68c0\u7d22\u6570\u636e\u3002 \u4f2a\u8868\u7684\u7528\u6cd5 \u4f2a\u8868 dual \u5e38\u7528\u4e8e\u4ee5\u4e0b\u573a\u666f\uff1a \u521d\u59cb\u5316\u5e8f\u5217\u548c\u6807\u8bc6\u5217\uff1a\u53ef\u4ee5\u4f7f\u7528 dual \u8868\u6765\u83b7\u53d6\u5e8f\u5217\u503c\u7684\u4e0b\u4e00\u4e2a\u503c\uff0c\u6216\u521d\u59cb\u5316\u6807\u8bc6\u5217\u7684\u503c\u3002 \u9a8c\u8bc1\u67e5\u8be2\u8bed\u6cd5\uff1a\u4ece dual \u8868\u4e2d\u68c0\u7d22\u6570\u636e\u53ef\u4ee5\u6d4b\u8bd5\u67e5\u8be2\u7684\u8bed\u6cd5\u662f\u5426\u6b63\u786e\uff0c\u800c\u65e0\u9700\u4f7f\u7528\u5b9e\u9645\u7684\u8868\u6570\u636e\u3002 \u63d0\u4f9b\u9ed8\u8ba4\u503c\uff1a\u5982\u679c\u5728\u67d0\u4e2a\u67e5\u8be2\u4e2d\u9700\u8981\u4e00\u4e2a\u9ed8\u8ba4\u503c\uff0c\u53ef\u4ee5\u4f7f\u7528 dual \u8868\u6765\u63d0\u4f9b\u8fd9\u4e2a\u503c\u3002 \u751f\u6210\u6d4b\u8bd5\u6570\u636e\uff1a\u53ef\u4ee5\u4f7f\u7528 dual \u8868\u6765\u751f\u6210\u4e00\u7ec4\u6d4b\u8bd5\u6570\u636e\uff0c\u4f8b\u5982\u7528\u4e8e\u6d4b\u8bd5\u51fd\u6570\u6216\u5b58\u50a8\u8fc7\u7a0b\u3002 \u4ee5\u4e0a\u5c31\u662fMySQL\u4f2a\u8868dual\u6709\u4ec0\u4e48\u4f5c\u7528\uff1f\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-6701","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/6701","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=6701"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/6701\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=6701"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=6701"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=6701"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}