{"id":5646,"date":"2024-11-14T09:51:28","date_gmt":"2024-11-14T01:51:28","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5646\/"},"modified":"2024-11-14T09:51:28","modified_gmt":"2024-11-14T01:51:28","slug":"sql%e4%b8%a4%e4%b8%aa%e8%a1%a8%e6%80%8e%e4%b9%88%e5%85%b3%e8%81%94","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5646\/","title":{"rendered":"sql\u4e24\u4e2a\u8868\u600e\u4e48\u5173\u8054"},"content":{"rendered":"<h2>\u5982\u4f55\u5173\u8054 SQL \u4e2d\u7684\u4e24\u4e2a\u8868<\/h2>\n<p><strong>\u6b65\u9aa4 1\uff1a\u660e\u786e\u5173\u8054\u7c7b\u578b<\/strong><\/p>\n<p>\u5728\u5173\u8054\u4e24\u4e2a\u8868\u4e4b\u524d\uff0c\u9700\u8981\u660e\u786e\u6240\u9700\u7684\u5173\u8054\u7c7b\u578b\uff1a<\/p>\n<ul>\n<li> <strong>\u5185\u8fde\u63a5\uff08INNER JOIN\uff09\uff1a<\/strong>\u4ec5\u68c0\u7d22\u6ee1\u8db3\u5173\u8054\u6761\u4ef6\u7684\u884c\u3002<\/li>\n<li> <strong>\u5916\u8fde\u63a5\uff08OUTER JOIN\uff09\uff1a<\/strong>\u68c0\u7d22\u6240\u6709\u884c\u7684\u7ed3\u679c\uff0c\u5373\u4f7f\u4e0d\u6ee1\u8db3\u5173\u8054\u6761\u4ef6\u3002<\/li>\n<\/ul>\n<p><strong>\u6b65\u9aa4 2\uff1a\u6307\u5b9a\u6761\u4ef6<\/strong><\/p>\n<p>\u4f7f\u7528 JOIN \u5173\u952e\u5b57\u5c06\u4e24\u4e2a\u8868\u5173\u8054\u8d77\u6765\uff0c\u5e76\u6307\u5b9a\u5173\u8054\u6761\u4ef6\u3002\u5173\u8054\u6761\u4ef6\u5fc5\u987b\u5728\u4e24\u4e2a\u8868\u4e4b\u95f4\u6709\u4e00\u4e2a\u5339\u914d\u7684\u5217\u3002<\/p>\n<p><strong>\u8bed\u6cd5\uff1a<\/strong><\/p>\n<pre>SELECT \u5217\u540d\nFROM \u8868\u540d1\nJOIN \u8868\u540d2 ON \u8868\u540d1.\u5173\u8054\u5217 = \u8868\u540d2.\u5173\u8054\u5217<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p><strong>\u6b65\u9aa4 3\uff1a\u9009\u62e9\u5173\u8054\u7c7b\u578b<\/strong><\/p>\n<p>\u6839\u636e\u9700\u8981\uff0c\u6307\u5b9a\u4ee5\u4e0b\u4efb\u4f55\u4e00\u79cd\u5173\u8054\u7c7b\u578b\uff1a<\/p>\n<ul>\n<li> <strong>INNER JOIN<\/strong>\uff1a\u8868\u540d1 INNER JOIN \u8868\u540d2 ON \u6761\u4ef6<\/li>\n<li> <strong>LEFT OUTER JOIN<\/strong>\uff1a\u8868\u540d1 LEFT OUTER JOIN \u8868\u540d2 ON \u6761\u4ef6<\/li>\n<li> <strong>RIGHT OUTER JOIN<\/strong>\uff1a\u8868\u540d1 RIGHT OUTER JOIN \u8868\u540d2 ON \u6761\u4ef6<\/li>\n<li> <strong>FULL OUTER JOIN<\/strong>\uff1a\u8868\u540d1 FULL OUTER JOIN \u8868\u540d2 ON \u6761\u4ef6<\/li>\n<\/ul>\n<p><strong>\u793a\u4f8b<\/strong><\/p>\n<p>\u5047\u8bbe\u6211\u4eec\u6709\u4e24\u4e2a\u8868\uff1a\u5b66\u751f \u548c \u6210\u7ee9\u3002\u6211\u4eec\u60f3\u67e5\u627e\u6240\u6709\u5b66\u751f\u7684\u5e73\u5747\u6210\u7ee9\uff0c\u6761\u4ef6\u662f\u5b66\u751fID\u5339\u914d\u3002<\/p>\n<p><strong>\u67e5\u8be2\uff1a<\/strong><\/p>\n<pre>SELECT s.\u5b66\u751f\u59d3\u540d, AVG(g.\u6210\u7ee9) AS \u5e73\u5747\u6210\u7ee9\nFROM \u5b66\u751f s\nINNER JOIN \u6210\u7ee9 g ON s.\u5b66\u751fID = g.\u5b66\u751fID<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p>\u8fd9\u5c06\u68c0\u7d22\u6240\u6709\u5b66\u751f\u53ca\u5176\u5e73\u5747\u6210\u7ee9\u3002<\/p>\n<p>\u4ee5\u4e0a\u5c31\u662fsql\u4e24\u4e2a\u8868\u600e\u4e48\u5173\u8054\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":"<p>\u5982\u4f55\u5173\u8054 SQL \u4e2d\u7684\u4e24\u4e2a\u8868 \u6b65\u9aa4 1\uff1a\u660e\u786e\u5173\u8054\u7c7b\u578b \u5728\u5173\u8054\u4e24\u4e2a\u8868\u4e4b\u524d\uff0c\u9700\u8981\u660e\u786e\u6240\u9700\u7684\u5173\u8054\u7c7b\u578b\uff1a \u5185\u8fde\u63a5\uff08INNER JOIN\uff09\uff1a\u4ec5\u68c0\u7d22\u6ee1\u8db3\u5173\u8054\u6761\u4ef6\u7684\u884c\u3002 \u5916\u8fde\u63a5\uff08OUTER JOIN\uff09\uff1a\u68c0\u7d22\u6240\u6709\u884c\u7684\u7ed3\u679c\uff0c\u5373\u4f7f\u4e0d\u6ee1\u8db3\u5173\u8054\u6761\u4ef6\u3002 \u6b65\u9aa4 2\uff1a\u6307\u5b9a\u6761\u4ef6 \u4f7f\u7528 JOIN \u5173\u952e\u5b57\u5c06\u4e24\u4e2a\u8868\u5173\u8054\u8d77\u6765\uff0c\u5e76\u6307\u5b9a\u5173\u8054\u6761\u4ef6\u3002\u5173\u8054\u6761\u4ef6\u5fc5\u987b\u5728\u4e24\u4e2a\u8868\u4e4b\u95f4\u6709\u4e00\u4e2a\u5339\u914d\u7684\u5217\u3002 \u8bed\u6cd5\uff1a SELECT \u5217\u540d FROM \u8868\u540d1 JOIN \u8868\u540d2 ON \u8868\u540d1.\u5173\u8054\u5217 = \u8868\u540d2.\u5173\u8054\u5217 \u767b\u5f55\u540e\u590d\u5236 \u6b65\u9aa4 3\uff1a\u9009\u62e9\u5173\u8054\u7c7b\u578b \u6839\u636e\u9700\u8981\uff0c\u6307\u5b9a\u4ee5\u4e0b\u4efb\u4f55\u4e00\u79cd\u5173\u8054\u7c7b\u578b\uff1a INNER JOIN\uff1a\u8868\u540d1 INNER JOIN \u8868\u540d2 ON \u6761\u4ef6 LEFT OUTER JOIN\uff1a\u8868\u540d1 LEFT OUTER JOIN \u8868\u540d2 ON \u6761\u4ef6 RIGHT OUTER JOIN\uff1a\u8868\u540d1 RIGHT OUTER JOIN \u8868\u540d2 ON \u6761\u4ef6 [&hellip;]<\/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-5646","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5646","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=5646"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5646\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5646"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5646"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5646"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}