{"id":200329,"date":"2025-05-06T09:25:13","date_gmt":"2025-05-06T01:25:13","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200329\/"},"modified":"2025-05-06T09:25:13","modified_gmt":"2025-05-06T01:25:13","slug":"sql-%e4%b8%ad%e7%9a%84-inner-join%e3%80%81left-join-%e5%92%8c-right-join%ef%bc%9a%e5%a6%82%e4%bd%95%e9%80%89%e6%8b%a9%e6%ad%a3%e7%a1%ae%e7%9a%84%e8%bf%9e%e6%8e%a5%e7%b1%bb%e5%9e%8b%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200329\/","title":{"rendered":"SQL \u4e2d\u7684 INNER JOIN\u3001LEFT JOIN \u548c RIGHT JOIN\uff1a\u5982\u4f55\u9009\u62e9\u6b63\u786e\u7684\u8fde\u63a5\u7c7b\u578b\uff1f"},"content":{"rendered":"

<\/b> <\/p>\n

SQL \u4e2d\u7684 INNER JOIN\u3001LEFT JOIN \u548c RIGHT JOIN\uff1a\u5982\u4f55\u9009\u62e9\u6b63\u786e\u7684\u8fde\u63a5\u7c7b\u578b\uff1f<\/h1>\n

\u73cd\u60dc\u65f6\u95f4\uff0c\u52e4\u594b\u5b66\u4e60\uff01\u4eca\u5929\u7ed9\u5927\u5bb6\u5e26\u6765\uff0c\u6b63\u6587\u5185\u5bb9\u4e3b\u8981\u6d89\u53ca\u5230\u7b49\u7b49\uff0c\u5982\u679c\u4f60\u6b63\u5728\u5b66\u4e60\uff0c\u6216\u8005\u662f\u5bf9\u6709\u7591\u95ee\uff0c\u6b22\u8fce\u5927\u5bb6\u5173\u6ce8\u6211\uff01\u540e\u9762\u6211\u4f1a\u6301\u7eed\u66f4\u65b0\u76f8\u5173\u5185\u5bb9\u7684\uff0c\u5e0c\u671b\u90fd\u80fd\u5e2e\u5230\u6b63\u5728\u5b66\u4e60\u7684\u5927\u5bb6\uff01<\/p>\n

<\/p>\n

\u5728\u6570\u636e\u67e5\u8be2\u4e2d\u9009\u62e9inner join\u3001left join\u548cright join<\/strong><\/p>\n

\u5728\u6d89\u53ca\u591a\u4e2a\u8868\u7684\u6570\u636e\u5e93\u64cd\u4f5c\u4e2d\uff0c\u7528\u4e8e\u8fde\u63a5\u8868\u5e76\u4ece\u4e2d\u63d0\u53d6\u6570\u636e\u7684\u8fde\u63a5\u7c7b\u578b\u6709\u591a\u79cd\uff0c\u5305\u62ecinner join\u3001left join\u548cright join\u3002<\/p>\n

\u5bf9\u4e8e\u521d\u5b66\u8005\u6765\u8bf4\uff0c\u533a\u5206\u8fd9\u4e9b\u8fde\u63a5\u7c7b\u578b\u5e76\u5728\u5b9e\u9645\u67e5\u8be2\u4e2d\u6b63\u786e\u4f7f\u7528\u5b83\u4eec\u53ef\u80fd\u4f1a\u4ee4\u4eba\u56f0\u60d1\u3002\u8fd9\u7bc7\u6587\u7ae0\u5c06\u6df1\u5165\u63a2\u8ba8\u4e0d\u540c\u8fde\u63a5\u7c7b\u578b\uff0c\u5e76\u63d0\u4f9b\u5177\u4f53\u793a\u4f8b\u6765\u8bf4\u660e\u4f55\u65f6\u4f7f\u7528\u5b83\u4eec\u3002<\/p>\n

inner join<\/strong><\/p>\n

inner join\u4ece\u8fde\u63a5\u8868\u4e2d\u4ec5\u9009\u62e9\u5177\u6709\u5339\u914d\u952e\u503c\u7684\u884c\u3002\u6362\u53e5\u8bdd\u8bf4\uff0c\u5b83\u53ea\u8fd4\u56de\u5b58\u5728\u4e8e\u4e24\u5f20\u8868\u4e2d\u7684\u8bb0\u5f55\u3002\u4f8b\u5982\uff0c\u5982\u679c\u8868a\u548cb\u5177\u6709\u76f8\u540c\u7684\u952e\u503c\u5217key\uff0c\u5219\u4e0b\u9762\u7684\u67e5\u8be2\u5c06\u8fd4\u56dekey\u5217\u5339\u914d\u7684\u884c\u7684\u5b50\u96c6\uff1a<\/p>\n

select * from a inner join b on a.key = b.key;<\/pre>\n
left join<\/strong><\/p>\n
left join\u4ece\u5de6\u8868\uff08\u8868a\uff09\u4e2d\u8fd4\u56de\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5b83\u4eec\u5728\u53f3\u8868\uff08\u8868b\uff09\u4e2d\u6ca1\u6709\u5339\u914d\u7684\u884c\u3002\u8fd9\u610f\u5473\u7740\u5b83\u8fd8\u4f1a\u8fd4\u56de\u53f3\u8868\u4e2d\u4e0d\u5b58\u5728\u7684\u503c\u3002left join\u67e5\u8be2\u901a\u5e38\u7528\u4e8e\u4ece\u5de6\u8868\u4e2d\u83b7\u53d6\u6570\u636e\uff0c\u5e76\u901a\u8fc7\u53f3\u8868\u4e2d\u7684\u5339\u914d\u884c\u5bf9\u5176\u8fdb\u884c\u8865\u5145\u3002<\/p>\n
select * from a left join b on a.key = b.key;<\/pre>\n
right join<\/strong><\/p>\n
right join\u4e0eleft join\u7c7b\u4f3c\uff0c\u4f46\u5b83\u4ece\u53f3\u8868\uff08\u8868b\uff09\u4e2d\u8fd4\u56de\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5b83\u4eec\u5728\u5de6\u8868\uff08\u8868a\uff09\u4e2d\u6ca1\u6709\u5339\u914d\u7684\u884c\u3002\u8fd9\u7c7b\u4f3c\u4e8e\u4ece\u53f3\u8868\u83b7\u53d6\u6570\u636e\u5e76\u901a\u8fc7\u5de6\u8868\u4e2d\u7684\u5339\u914d\u884c\u5bf9\u5176\u8fdb\u884c\u8865\u5145\u3002<\/p>\n
SELECT * FROM A RIGHT JOIN B ON A.key = B.key;<\/pre>\n
\u9009\u62e9\u6b63\u786e\u7684\u8fde\u63a5\u7c7b\u578b<\/strong><\/p>\n
\u9009\u62e9\u6b63\u786e\u7684\u8fde\u63a5\u7c7b\u578b\u53d6\u51b3\u4e8e\u4ee5\u4e0b\u56e0\u7d20\uff1a<\/p>\n
    \n
  • \u6240\u9700\u7684\u6570\u636e\uff1a<\/strong>\u4f60\u60f3\u83b7\u53d6\u4e24\u8868\u4e2d\u5339\u914d\u7684\u884c\u3001\u5de6\u8868\u4e2d\u7684\u6240\u6709\u884c\u8fd8\u662f\u53f3\u8868\u4e2d\u7684\u6240\u6709\u884c\uff1f<\/li>\n
  • \u952e\u503c\u5217\u7684\u5904\u7406\uff1a<\/strong>\u952e\u503c\u5217\u662f\u5426\u5141\u8bb8\u4e3anull\u503c\uff1f\u5982\u679c\u5141\u8bb8\uff0c\u5219\u9700\u8981\u8003\u8651\u4f7f\u7528left join\u6216right join\u6765\u5904\u7406\u7f3a\u5c11\u5339\u914d\u7684\u884c\u3002<\/li>\n<\/ul>\n
    \u901a\u8fc7\u7406\u89e3inner join\u3001left join\u548cright join\u4e4b\u95f4\u7684\u5dee\u5f02\uff0c\u4ee5\u53ca\u5b83\u4eec\u5728\u4e0d\u540c\u60c5\u51b5\u4e0b\u7684\u5e94\u7528\uff0c\u4f60\u53ef\u4ee5\u7f16\u5199\u66f4\u6709\u6548\u548c\u51c6\u786e\u7684\u6570\u636e\u5e93\u67e5\u8be2\u3002<\/p>\n
    \u7406\u8bba\u8981\u638c\u63e1\uff0c\u5b9e\u64cd\u4e0d\u80fd\u843d\uff01\u4ee5\u4e0a\u5173\u4e8e\u300aSQL \u4e2d\u7684 INNER JOIN\u3001LEFT JOIN \u548c RIGHT JOIN\uff1a\u5982\u4f55\u9009\u62e9\u6b63\u786e\u7684\u8fde\u63a5\u7c7b\u578b\uff1f\u300b\u7684\u8be6\u7ec6\u4ecb\u7ecd\uff0c\u5927\u5bb6\u90fd\u638c\u63e1\u4e86\u5427\uff01\u5982\u679c\u60f3\u8981\u7ee7\u7eed\u63d0\u5347\u81ea\u5df1\u7684\u80fd\u529b\uff0c\u90a3\u4e48\u5c31\u6765\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u5427\uff01<\/p>\n
    \n
    \n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"
    SQL \u4e2d\u7684 INNER JOI...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-200329","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200329","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=200329"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200329\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200329"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200329"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200329"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}