{"id":186834,"date":"2024-11-11T09:13:29","date_gmt":"2024-11-11T01:13:29","guid":{"rendered":"https:\/\/server.hk\/cnblog\/186834\/"},"modified":"2024-11-11T09:13:30","modified_gmt":"2024-11-11T01:13:30","slug":"%e6%95%b8%e6%93%9a%e5%ba%ab%e9%80%a3%e6%8e%a5%ef%bc%9a%e5%a4%9a%e8%a1%a8%e6%9f%a5%e8%a9%a2%e6%8a%80%e5%b7%a7-%e4%b8%8d%e5%90%8c%e6%95%b8%e6%93%9a%e5%ba%ab%e9%80%a3%e8%a1%a8%e6%9f%a5%e8%a9%a2","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/186834\/","title":{"rendered":"\u6578\u64da\u5eab\u9023\u63a5\uff1a\u591a\u8868\u67e5\u8a62\u6280\u5de7 (\u4e0d\u540c\u6578\u64da\u5eab\u9023\u8868\u67e5\u8a62)"},"content":{"rendered":"<h1 id=\"%e6%95%b8%e6%93%9a%e5%ba%ab%e9%80%a3%e6%8e%a5%ef%bc%9a%e5%a4%9a%e8%a1%a8%e6%9f%a5%e8%a9%a2%e6%8a%80%e5%b7%a7-%e4%b8%8d%e5%90%8c%e6%95%b8%e6%93%9a%e5%ba%ab%e9%80%a3%e8%a1%a8%e6%9f%a5%e8%a9%a2-lWOtHfmENn\">\u6578\u64da\u5eab\u9023\u63a5\uff1a\u591a\u8868\u67e5\u8a62\u6280\u5de7 (\u4e0d\u540c\u6578\u64da\u5eab\u9023\u8868\u67e5\u8a62)<\/h1>\n<p>\u5728\u73fe\u4eca\u7684\u6578\u64da\u9a45\u52d5\u6642\u4ee3\uff0c\u6578\u64da\u5eab\u7684\u4f7f\u7528\u5df2\u6210\u70ba\u5404\u884c\u5404\u696d\u4e0d\u53ef\u6216\u7f3a\u7684\u4e00\u90e8\u5206\u3002\u5c24\u5176\u662f\u5728\u9700\u8981\u8655\u7406\u5927\u91cf\u6578\u64da\u7684\u61c9\u7528\u4e2d\uff0c\u5982\u4f55\u6709\u6548\u5730\u9032\u884c\u591a\u8868\u67e5\u8a62\u6210\u70ba\u4e86\u958b\u767c\u8005\u5fc5\u9808\u638c\u63e1\u7684\u6280\u80fd\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u4e0d\u540c\u6578\u64da\u5eab\u4e4b\u9593\u7684\u9023\u8868\u67e5\u8a62\u6280\u5de7\uff0c\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u548c\u61c9\u7528\u9019\u4e9b\u6280\u8853\u3002<\/p>\n<h2 id=\"%e5%a4%9a%e8%a1%a8%e6%9f%a5%e8%a9%a2%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-lWOtHfmENn\">\u591a\u8868\u67e5\u8a62\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>\u591a\u8868\u67e5\u8a62\u662f\u6307\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u540c\u6642\u5f9e\u591a\u500b\u8868\u4e2d\u6aa2\u7d22\u6578\u64da\u3002\u9019\u901a\u5e38\u6d89\u53ca\u5230\u4f7f\u7528 SQL \u8a9e\u8a00\u4e2d\u7684 JOIN \u64cd\u4f5c\u3002JOIN \u64cd\u4f5c\u53ef\u4ee5\u6839\u64da\u67d0\u4e9b\u689d\u4ef6\u5c07\u591a\u500b\u8868\u4e2d\u7684\u6578\u64da\u7d50\u5408\u8d77\u4f86\uff0c\u5f9e\u800c\u63d0\u4f9b\u66f4\u5168\u9762\u7684\u4fe1\u606f\u3002<\/p>\n<h3 id=\"join-%e7%9a%84%e9%a1%9e%e5%9e%8b-lWOtHfmENn\">JOIN \u7684\u985e\u578b<\/h3>\n<ul>\n<li><strong>INNER JOIN<\/strong>: \u53ea\u8fd4\u56de\u5169\u500b\u8868\u4e2d\u5339\u914d\u7684\u884c\u3002<\/li>\n<li><strong>LEFT JOIN<\/strong>: \u8fd4\u56de\u5de6\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u53f3\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\u3002<\/li>\n<li><strong>RIGHT JOIN<\/strong>: \u8fd4\u56de\u53f3\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5de6\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\u3002<\/li>\n<li><strong>FULL OUTER JOIN<\/strong>: \u8fd4\u56de\u5169\u500b\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u7121\u8ad6\u662f\u5426\u6709\u5339\u914d\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%b8%8d%e5%90%8c%e6%95%b8%e6%93%9a%e5%ba%ab%e7%9a%84%e9%80%a3%e8%a1%a8%e6%9f%a5%e8%a9%a2%e6%8a%80%e5%b7%a7-lWOtHfmENn\">\u4e0d\u540c\u6578\u64da\u5eab\u7684\u9023\u8868\u67e5\u8a62\u6280\u5de7<\/h2>\n<p>\u4e0d\u540c\u7684\u6578\u64da\u5eab\u7cfb\u7d71\uff08\u5982 MySQL\u3001PostgreSQL\u3001SQL Server \u7b49\uff09\u5728\u8a9e\u6cd5\u4e0a\u53ef\u80fd\u6703\u6709\u4e9b\u8a31\u5dee\u7570\uff0c\u4f46\u57fa\u672c\u7684\u67e5\u8a62\u908f\u8f2f\u662f\u76f8\u4f3c\u7684\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u9023\u8868\u67e5\u8a62\u793a\u4f8b\uff1a<\/p>\n<h3 id=\"mysql-%e4%b8%ad%e7%9a%84%e5%a4%9a%e8%a1%a8%e6%9f%a5%e8%a9%a2-lWOtHfmENn\">MySQL \u4e2d\u7684\u591a\u8868\u67e5\u8a62<\/h3>\n<pre><code>SELECT a.column1, b.column2\nFROM table_a AS a\nINNER JOIN table_b AS b ON a.id = b.a_id\nWHERE a.status = 'active';<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6211\u5011\u5f9e <code>table_a<\/code> \u548c <code>table_b<\/code> \u4e2d\u9078\u64c7\u4e86\u7279\u5b9a\u7684\u5217\uff0c\u4e26\u901a\u904e <code>INNER JOIN<\/code> \u5c07\u5b83\u5011\u9023\u63a5\u8d77\u4f86\uff0c\u689d\u4ef6\u662f <code>table_a<\/code> \u7684 <code>id<\/code> \u8207 <code>table_b<\/code> \u7684 <code>a_id<\/code> \u76f8\u5339\u914d\u3002<\/p>\n<h3 id=\"postgresql-%e4%b8%ad%e7%9a%84%e5%a4%9a%e8%a1%a8%e6%9f%a5%e8%a9%a2-lWOtHfmENn\">PostgreSQL \u4e2d\u7684\u591a\u8868\u67e5\u8a62<\/h3>\n<pre><code>SELECT a.column1, b.column2\nFROM table_a a\nLEFT JOIN table_b b ON a.id = b.a_id\nWHERE a.created_at &gt; '2023-01-01';<\/code><\/pre>\n<p>\u5728 PostgreSQL \u4e2d\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528 <code>LEFT JOIN<\/code> \u4f86\u7372\u53d6\u6240\u6709\u4f86\u81ea <code>table_a<\/code> \u7684\u884c\uff0c\u5373\u4f7f\u5728 <code>table_b<\/code> \u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\u3002\u9019\u5c0d\u65bc\u9700\u8981\u4fdd\u7559\u6240\u6709\u4e3b\u8868\u6578\u64da\u7684\u60c5\u6cc1\u7279\u5225\u6709\u7528\u3002<\/p>\n<h3 id=\"sql-server-%e4%b8%ad%e7%9a%84%e5%a4%9a%e8%a1%a8%e6%9f%a5%e8%a9%a2-lWOtHfmENn\">SQL Server \u4e2d\u7684\u591a\u8868\u67e5\u8a62<\/h3>\n<pre><code>SELECT a.column1, b.column2\nFROM table_a AS a\nFULL OUTER JOIN table_b AS b ON a.id = b.a_id\nWHERE b.column2 IS NOT NULL;<\/code><\/pre>\n<p>\u5728 SQL Server \u4e2d\uff0c<code>FULL OUTER JOIN<\/code> \u53ef\u4ee5\u7528\u4f86\u7372\u53d6\u5169\u500b\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u4e26\u4e14\u53ef\u4ee5\u901a\u904e <code>WHERE<\/code> \u5b50\u53e5\u9032\u4e00\u6b65\u904e\u6ffe\u7d50\u679c\u3002<\/p>\n<h2 id=\"%e6%80%a7%e8%83%bd%e8%80%83%e9%87%8f-lWOtHfmENn\">\u6027\u80fd\u8003\u91cf<\/h2>\n<p>\u5728\u9032\u884c\u591a\u8868\u67e5\u8a62\u6642\uff0c\u6027\u80fd\u662f\u4e00\u500b\u91cd\u8981\u7684\u8003\u91cf\u56e0\u7d20\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u512a\u5316\u67e5\u8a62\u6027\u80fd\u7684\u6280\u5de7\uff1a<\/p>\n<ul>\n<li>\u78ba\u4fdd\u5728\u9023\u63a5\u7684\u5217\u4e0a\u5efa\u7acb\u7d22\u5f15\uff0c\u4ee5\u52a0\u5feb\u67e5\u8a62\u901f\u5ea6\u3002<\/li>\n<li>\u907f\u514d\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528 SELECT *\uff0c\u800c\u662f\u9078\u64c7\u9700\u8981\u7684\u5217\u3002<\/li>\n<li>\u4f7f\u7528\u9069\u7576\u7684 JOIN \u985e\u578b\uff0c\u6839\u64da\u9700\u6c42\u9078\u64c7 INNER\u3001LEFT \u6216 FULL JOIN\u3002<\/li>\n<li>\u5b9a\u671f\u6aa2\u67e5\u548c\u512a\u5316\u6578\u64da\u5eab\u7684\u6027\u80fd\uff0c\u78ba\u4fdd\u67e5\u8a62\u6548\u7387\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-lWOtHfmENn\">\u7e3d\u7d50<\/h2>\n<p>\u591a\u8868\u67e5\u8a62\u662f\u6578\u64da\u5eab\u64cd\u4f5c\u4e2d\u4e00\u500b\u91cd\u8981\u7684\u6280\u8853\uff0c\u638c\u63e1\u4e0d\u540c\u6578\u64da\u5eab\u7684\u9023\u8868\u67e5\u8a62\u6280\u5de7\u80fd\u5920\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u6709\u6548\u5730\u8655\u7406\u6578\u64da\u3002\u5728\u9999\u6e2f\u7684\u6578\u64da\u4e2d\u5fc3\u4e2d\uff0c\u9078\u64c7\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u65b9\u6848\u53ef\u4ee5\u70ba\u60a8\u7684\u61c9\u7528\u63d0\u4f9b\u7a69\u5b9a\u7684\u6578\u64da\u5eab\u652f\u6301\uff0c\u7121\u8ad6\u662f\u4f7f\u7528 MySQL\u3001PostgreSQL \u9084\u662f SQL Server\uff0c\u5747\u80fd\u5920\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002\u4e86\u89e3\u9019\u4e9b\u67e5\u8a62\u6280\u5de7\uff0c\u5c07\u4f7f\u60a8\u5728\u6578\u64da\u7ba1\u7406\u4e0a\u66f4\u52a0\u5f97\u5fc3\u61c9\u624b\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u638c\u63e1\u591a\u8868\u67e5\u8a62\u6280\u5de7\uff0c\u5b78\u7fd2\u5982\u4f55\u5728\u4e0d\u540c\u6578\u64da\u5eab\u4e2d\u6709\u6548\u9023\u63a5\u548c\u67e5\u8a62\u6578\u64da\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\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-186834","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186834","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=186834"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186834\/revisions"}],"predecessor-version":[{"id":186835,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186834\/revisions\/186835"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=186834"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=186834"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=186834"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}