{"id":96314,"date":"2024-10-20T08:23:16","date_gmt":"2024-10-20T00:23:16","guid":{"rendered":"https:\/\/server.hk\/cnblog\/96314\/"},"modified":"2024-10-20T08:23:16","modified_gmt":"2024-10-20T00:23:16","slug":"oracle%e5%b7%a6%e9%80%a3%e6%8e%a5left-join-%e7%9a%84%e5%af%a6%e9%9a%9b%e6%93%8d%e4%bd%9c%e8%88%87%e6%87%89%e7%94%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/96314\/","title":{"rendered":"Oracle\u5de6\u9023\u63a5left join \u7684\u5be6\u969b\u64cd\u4f5c\u8207\u61c9\u7528"},"content":{"rendered":"<h1 id=\"oracle%e5%b7%a6%e9%80%a3%e6%8e%a5left-join%e7%9a%84%e5%af%a6%e9%9a%9b%e6%93%8d%e4%bd%9c%e8%88%87%e6%87%89%e7%94%a8-ODkVdGfQKB\">Oracle\u5de6\u9023\u63a5(LEFT JOIN)\u7684\u5be6\u969b\u64cd\u4f5c\u8207\u61c9\u7528<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0c\u5de6\u9023\u63a5\uff08LEFT JOIN\uff09\u662f\u4e00\u7a2e\u975e\u5e38\u91cd\u8981\u7684\u67e5\u8a62\u6280\u8853\uff0c\u5c24\u5176\u662f\u5728\u8655\u7406\u591a\u500b\u8cc7\u6599\u8868\u4e4b\u9593\u7684\u95dc\u806f\u6642\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eOracle\u8cc7\u6599\u5eab\u4e2d\u5de6\u9023\u63a5\u7684\u5be6\u969b\u64cd\u4f5c\u8207\u61c9\u7528\uff0c\u4e26\u63d0\u4f9b\u76f8\u95dc\u7684\u7bc4\u4f8b\u8207\u4ee3\u78bc\uff0c\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u9019\u4e00\u6982\u5ff5\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af%e5%b7%a6%e9%80%a3%e6%8e%a5left-join-ODkVdGfQKB\">\u4ec0\u9ebc\u662f\u5de6\u9023\u63a5(LEFT JOIN)?<\/h2>\n<p>\u5de6\u9023\u63a5\u662f\u4e00\u7a2e\u806f\u63a5\u64cd\u4f5c\uff0c\u4e3b\u8981\u7528\u65bc\u5f9e\u5169\u500b\u6216\u591a\u500b\u8cc7\u6599\u8868\u4e2d\u6aa2\u7d22\u8cc7\u6599\u3002\u5b83\u7684\u7279\u9ede\u662f\u8fd4\u56de\u5de6\u5074\u8cc7\u6599\u8868\u4e2d\u7684\u6240\u6709\u8a18\u9304\uff0c\u5373\u4f7f\u53f3\u5074\u8cc7\u6599\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u8a18\u9304\u3002\u5728\u9019\u7a2e\u60c5\u6cc1\u4e0b\uff0c\u53f3\u5074\u8cc7\u6599\u8868\u7684\u6b04\u4f4d\u5c07\u986f\u793a\u70baNULL\u3002<\/p>\n<h2 id=\"%e5%b7%a6%e9%80%a3%e6%8e%a5%e7%9a%84%e8%aa%9e%e6%b3%95-ODkVdGfQKB\">\u5de6\u9023\u63a5\u7684\u8a9e\u6cd5<\/h2>\n<p>\u5728Oracle\u4e2d\uff0c\u5de6\u9023\u63a5\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SELECT \u5217\u540d1, \u5217\u540d2, ...\nFROM \u88681\nLEFT JOIN \u88682\nON \u88681.\u6b04\u4f4d = \u88682.\u6b04\u4f4d;<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c\u88681\u662f\u5de6\u5074\u8cc7\u6599\u8868\uff0c\u88682\u662f\u53f3\u5074\u8cc7\u6599\u8868\u3002ON\u5b50\u53e5\u7528\u65bc\u6307\u5b9a\u5169\u500b\u8cc7\u6599\u8868\u4e4b\u9593\u7684\u806f\u63a5\u689d\u4ef6\u3002<\/p>\n<h2 id=\"%e5%b7%a6%e9%80%a3%e6%8e%a5%e7%9a%84%e5%af%a6%e9%9a%9b%e7%af%84%e4%be%8b-ODkVdGfQKB\">\u5de6\u9023\u63a5\u7684\u5be6\u969b\u7bc4\u4f8b<\/h2>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u5169\u500b\u8cc7\u6599\u8868\uff1a<strong>\u54e1\u5de5<\/strong>\uff08employees\uff09\u548c<strong>\u90e8\u9580<\/strong>\uff08departments\uff09\u3002\u54e1\u5de5\u8cc7\u6599\u8868\u5305\u542b\u6bcf\u4f4d\u54e1\u5de5\u7684ID\u3001\u59d3\u540d\u548c\u90e8\u9580ID\uff0c\u800c\u90e8\u9580\u8cc7\u6599\u8868\u5247\u5305\u542b\u90e8\u9580ID\u548c\u90e8\u9580\u540d\u7a31\u3002<\/p>\n<p>\u4ee5\u4e0b\u662f\u9019\u5169\u500b\u8cc7\u6599\u8868\u7684\u7d50\u69cb\uff1a<\/p>\n<ul>\n<li><strong>employees<\/strong>\n<ul>\n<li>employee_id<\/li>\n<li>employee_name<\/li>\n<li>department_id<\/li>\n<\/ul>\n<\/li>\n<li><strong>departments<\/strong>\n<ul>\n<li>department_id<\/li>\n<li>department_name<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>\u5982\u679c\u6211\u5011\u60f3\u8981\u67e5\u8a62\u6240\u6709\u54e1\u5de5\u53ca\u5176\u6240\u5c6c\u90e8\u9580\u7684\u540d\u7a31\uff0c\u5373\u4f7f\u67d0\u4e9b\u54e1\u5de5\u6c92\u6709\u90e8\u9580\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528\u5de6\u9023\u63a5\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<pre><code>SELECT e.employee_id, e.employee_name, d.department_name\nFROM employees e\nLEFT JOIN departments d\nON e.department_id = d.department_id;<\/code><\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u6240\u6709\u54e1\u5de5\u7684ID\u548c\u59d3\u540d\uff0c\u4e26\u4e14\u5982\u679c\u67d0\u4f4d\u54e1\u5de5\u6c92\u6709\u5c0d\u61c9\u7684\u90e8\u9580\uff0c\u5247\u90e8\u9580\u540d\u7a31\u5c07\u986f\u793a\u70baNULL\u3002<\/p>\n<h2 id=\"%e5%b7%a6%e9%80%a3%e6%8e%a5%e7%9a%84%e6%87%89%e7%94%a8%e5%a0%b4%e6%99%af-ODkVdGfQKB\">\u5de6\u9023\u63a5\u7684\u61c9\u7528\u5834\u666f<\/h2>\n<p>\u5de6\u9023\u63a5\u5728\u5be6\u969b\u61c9\u7528\u4e2d\u6709\u591a\u7a2e\u5834\u666f\uff0c\u4ee5\u4e0b\u662f\u5e7e\u500b\u5e38\u898b\u7684\u4f8b\u5b50\uff1a<\/p>\n<ul>\n<li><strong>\u5831\u544a\u751f\u6210\uff1a<\/strong>\u5728\u751f\u6210\u5831\u544a\u6642\uff0c\u53ef\u80fd\u9700\u8981\u986f\u793a\u6240\u6709\u8a18\u9304\uff0c\u5373\u4f7f\u67d0\u4e9b\u8a18\u9304\u6c92\u6709\u76f8\u95dc\u7684\u8a73\u7d30\u8cc7\u6599\u3002<\/li>\n<li><strong>\u6578\u64da\u6574\u5408\uff1a<\/strong>\u5728\u6578\u64da\u6574\u5408\u904e\u7a0b\u4e2d\uff0c\u5de6\u9023\u63a5\u53ef\u4ee5\u5e6b\u52a9\u5f9e\u591a\u500b\u8cc7\u6599\u8868\u4e2d\u63d0\u53d6\u5fc5\u8981\u7684\u8cc7\u8a0a\u3002<\/li>\n<li><strong>\u6578\u64da\u5206\u6790\uff1a<\/strong>\u5728\u9032\u884c\u6578\u64da\u5206\u6790\u6642\uff0c\u5de6\u9023\u63a5\u53ef\u4ee5\u5e6b\u52a9\u5206\u6790\u67d0\u4e9b\u8cc7\u6599\u8868\u4e2d\u7684\u7f3a\u5931\u503c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-ODkVdGfQKB\">\u7e3d\u7d50<\/h2>\n<p>\u5de6\u9023\u63a5\uff08LEFT JOIN\uff09\u662f\u4e00\u7a2e\u5f37\u5927\u7684\u67e5\u8a62\u5de5\u5177\uff0c\u80fd\u5920\u6709\u6548\u5730\u5f9e\u591a\u500b\u8cc7\u6599\u8868\u4e2d\u63d0\u53d6\u6240\u9700\u7684\u8cc7\u8a0a\u3002\u900f\u904e\u6b63\u78ba\u7684\u8a9e\u6cd5\u548c\u61c9\u7528\u5834\u666f\uff0c\u4f7f\u7528\u8005\u53ef\u4ee5\u8f15\u9b06\u5730\u7372\u53d6\u5b8c\u6574\u7684\u6578\u64da\u96c6\uff0c\u7121\u8ad6\u662f\u7528\u65bc\u5831\u544a\u751f\u6210\u3001\u6578\u64da\u6574\u5408\u9084\u662f\u6578\u64da\u5206\u6790\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u4f01\u696d\u4f86\u8aaa\uff0c\u9078\u64c7\u5408\u9069\u7684\u8cc7\u6599\u5eab\u89e3\u6c7a\u65b9\u6848\u81f3\u95dc\u91cd\u8981\u3002\u82e5\u60a8\u5c0d\u65bc<code>VPS<\/code>\u3001<code>\u9999\u6e2fVPS<\/code>\u6216<code>\u4f3a\u670d\u5668<\/code>\u7b49\u76f8\u95dc\u670d\u52d9\u611f\u8208\u8da3\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9 <a href=\"https:\/\/server.hk\">Server.HK<\/a> \u7372\u53d6\u66f4\u591a\u8cc7\u8a0a\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22Oracle\u5de6\u9023\u63a5\uff08LEFT JOIN\uff09\u7684\u5be6\u969b\u64cd\u4f5c\u8207\u61c9\u7528\uff0c\u4e86\u89e3\u5982\u4f55\u6709\u6548\u6574\u5408\u6578\u64da\u4ee5\u63d0\u5347\u67e5\u8a62\u6548\u7387\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-96314","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/96314","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=96314"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/96314\/revisions"}],"predecessor-version":[{"id":96315,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/96314\/revisions\/96315"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=96314"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=96314"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=96314"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}