{"id":160819,"date":"2024-11-04T01:16:34","date_gmt":"2024-11-03T17:16:34","guid":{"rendered":"https:\/\/server.hk\/cnblog\/160819\/"},"modified":"2024-11-04T01:16:34","modified_gmt":"2024-11-03T17:16:34","slug":"%e8%b3%87%e6%96%99%e5%ba%ab%e6%95%99%e7%a8%8b%ef%bc%9amysql-%e5%ad%90%e6%9f%a5%e8%a9%a2%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/160819\/","title":{"rendered":"\u8cc7\u6599\u5eab\u6559\u7a0b\uff1aMySQL \u5b50\u67e5\u8a62\u6ce8\u610f\u4e8b\u9805"},"content":{"rendered":"<h1 id=\"%e8%b3%87%e6%96%99%e5%ba%ab%e6%95%99%e7%a8%8b%ef%bc%9amysql-%e5%ad%90%e6%9f%a5%e8%a9%a2%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-LLWaemRnuH\">\u8cc7\u6599\u5eab\u6559\u7a0b\uff1aMySQL \u5b50\u67e5\u8a62\u6ce8\u610f\u4e8b\u9805<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cMySQL \u662f\u4e00\u500b\u5ee3\u6cdb\u4f7f\u7528\u7684\u958b\u6e90\u8cc7\u6599\u5eab\uff0c\u7279\u5225\u662f\u5728\u7db2\u9801\u61c9\u7528\u7a0b\u5f0f\u4e2d\u3002\u5b50\u67e5\u8a62\uff08Subquery\uff09\u662f MySQL \u4e2d\u4e00\u500b\u5f37\u5927\u7684\u529f\u80fd\uff0c\u5141\u8a31\u7528\u6236\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u5d4c\u5957\u53e6\u4e00\u500b\u67e5\u8a62\u3002\u96d6\u7136\u5b50\u67e5\u8a62\u63d0\u4f9b\u4e86\u9748\u6d3b\u6027\u548c\u5f37\u5927\u7684\u67e5\u8a62\u80fd\u529b\uff0c\u4f46\u5728\u4f7f\u7528\u6642\u4e5f\u6709\u4e00\u4e9b\u6ce8\u610f\u4e8b\u9805\u9700\u8981\u8003\u616e\u3002\u672c\u6587\u5c07\u63a2\u8a0e MySQL \u5b50\u67e5\u8a62\u7684\u57fa\u672c\u6982\u5ff5\u3001\u4f7f\u7528\u60c5\u5883\u53ca\u5176\u6ce8\u610f\u4e8b\u9805\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af%e5%ad%90%e6%9f%a5%e8%a9%a2%ef%bc%9f-LLWaemRnuH\">\u4ec0\u9ebc\u662f\u5b50\u67e5\u8a62\uff1f<\/h2>\n<p>\u5b50\u67e5\u8a62\u662f\u6307\u5728\u4e00\u500b SQL \u67e5\u8a62\u4e2d\u5d4c\u5957\u7684\u53e6\u4e00\u500b\u67e5\u8a62\u3002\u5b50\u67e5\u8a62\u53ef\u4ee5\u7528\u65bc SELECT\u3001INSERT\u3001UPDATE \u6216 DELETE \u8a9e\u53e5\u4e2d\uff0c\u4e26\u4e14\u53ef\u4ee5\u8fd4\u56de\u55ae\u4e00\u503c\u3001\u884c\u6216\u591a\u884c\u6578\u64da\u3002\u5b50\u67e5\u8a62\u901a\u5e38\u7528\u65bc\u9700\u8981\u6839\u64da\u5176\u4ed6\u67e5\u8a62\u7684\u7d50\u679c\u4f86\u904e\u6ffe\u6216\u8a08\u7b97\u6578\u64da\u7684\u60c5\u6cc1\u3002<\/p>\n<h2 id=\"%e5%ad%90%e6%9f%a5%e8%a9%a2%e7%9a%84%e9%a1%9e%e5%9e%8b-LLWaemRnuH\">\u5b50\u67e5\u8a62\u7684\u985e\u578b<\/h2>\n<ul>\n<li><strong>\u55ae\u884c\u5b50\u67e5\u8a62\uff1a<\/strong>\u8fd4\u56de\u55ae\u4e00\u884c\u7684\u7d50\u679c\u3002<\/li>\n<li><strong>\u591a\u884c\u5b50\u67e5\u8a62\uff1a<\/strong>\u8fd4\u56de\u591a\u884c\u7684\u7d50\u679c\u3002<\/li>\n<li><strong>\u76f8\u95dc\u5b50\u67e5\u8a62\uff1a<\/strong>\u4f9d\u8cf4\u65bc\u5916\u90e8\u67e5\u8a62\u7684\u7d50\u679c\u3002<\/li>\n<li><strong>\u975e\u76f8\u95dc\u5b50\u67e5\u8a62\uff1a<\/strong>\u7368\u7acb\u65bc\u5916\u90e8\u67e5\u8a62\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e5%ad%90%e6%9f%a5%e8%a9%a2%e7%9a%84%e6%83%85%e5%a2%83-LLWaemRnuH\">\u4f7f\u7528\u5b50\u67e5\u8a62\u7684\u60c5\u5883<\/h2>\n<p>\u5b50\u67e5\u8a62\u901a\u5e38\u7528\u65bc\u4ee5\u4e0b\u60c5\u5883\uff1a<\/p>\n<ul>\n<li>\u9700\u8981\u5f9e\u4e00\u500b\u8868\u4e2d\u9078\u64c7\u6578\u64da\uff0c\u4e26\u6839\u64da\u53e6\u4e00\u500b\u8868\u7684\u6578\u64da\u9032\u884c\u904e\u6ffe\u3002<\/li>\n<li>\u8a08\u7b97\u805a\u5408\u503c\uff0c\u4f8b\u5982\u8a08\u7b97\u67d0\u500b\u90e8\u9580\u7684\u5e73\u5747\u85aa\u8cc7\u3002<\/li>\n<li>\u5728 INSERT \u6216 UPDATE \u64cd\u4f5c\u4e2d\u4f7f\u7528\u5176\u4ed6\u8868\u7684\u6578\u64da\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%ad%90%e6%9f%a5%e8%a9%a2%e7%9a%84%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-LLWaemRnuH\">\u5b50\u67e5\u8a62\u7684\u6ce8\u610f\u4e8b\u9805<\/h2>\n<h3 id=\"1-%e6%80%a7%e8%83%bd%e5%95%8f%e9%a1%8c-LLWaemRnuH\">1. \u6027\u80fd\u554f\u984c<\/h3>\n<p>\u96d6\u7136\u5b50\u67e5\u8a62\u63d0\u4f9b\u4e86\u9748\u6d3b\u6027\uff0c\u4f46\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528\u5b50\u67e5\u8a62\u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u4e0b\u964d\u3002\u7279\u5225\u662f\u7576\u5b50\u67e5\u8a62\u8fd4\u56de\u5927\u91cf\u6578\u64da\u6642\uff0c\u67e5\u8a62\u7684\u57f7\u884c\u901f\u5ea6\u53ef\u80fd\u6703\u53d7\u5230\u5f71\u97ff\u3002\u5efa\u8b70\u5728\u53ef\u80fd\u7684\u60c5\u6cc1\u4e0b\u4f7f\u7528 JOIN \u4f86\u66ff\u4ee3\u5b50\u67e5\u8a62\uff0c\u4ee5\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/p>\n<h3 id=\"2-%e5%8f%af%e8%ae%80%e6%80%a7-LLWaemRnuH\">2. \u53ef\u8b80\u6027<\/h3>\n<p>\u904e\u591a\u7684\u5d4c\u5957\u5b50\u67e5\u8a62\u53ef\u80fd\u6703\u4f7f SQL \u8a9e\u53e5\u8b8a\u5f97\u96e3\u4ee5\u95b1\u8b80\u548c\u7dad\u8b77\u3002\u70ba\u4e86\u63d0\u9ad8\u53ef\u8b80\u6027\uff0c\u5efa\u8b70\u5c07\u8907\u96dc\u7684\u67e5\u8a62\u62c6\u5206\u70ba\u591a\u500b\u7c21\u55ae\u7684\u67e5\u8a62\uff0c\u6216\u8005\u4f7f\u7528\u8996\u5716\uff08View\uff09\u4f86\u7c21\u5316\u67e5\u8a62\u7d50\u69cb\u3002<\/p>\n<h3 id=\"3-%e8%bf%94%e5%9b%9e%e5%80%bc%e7%9a%84%e9%a1%9e%e5%9e%8b-LLWaemRnuH\">3. \u8fd4\u56de\u503c\u7684\u985e\u578b<\/h3>\n<p>\u5728\u4f7f\u7528\u5b50\u67e5\u8a62\u6642\uff0c\u5fc5\u9808\u78ba\u4fdd\u5b50\u67e5\u8a62\u8fd4\u56de\u7684\u503c\u8207\u5916\u90e8\u67e5\u8a62\u7684\u8981\u6c42\u76f8\u7b26\u3002\u4f8b\u5982\uff0c\u7576\u4f7f\u7528\u55ae\u884c\u5b50\u67e5\u8a62\u6642\uff0c\u5fc5\u9808\u78ba\u4fdd\u5b50\u67e5\u8a62\u53ea\u8fd4\u56de\u4e00\u884c\u4e00\u5217\u7684\u7d50\u679c\uff0c\u5426\u5247\u6703\u5c0e\u81f4\u932f\u8aa4\u3002<\/p>\n<pre><code>SELECT name FROM employees WHERE salary = (SELECT MAX(salary) FROM employees);<\/code><\/pre>\n<h3 id=\"4-%e7%9b%b8%e9%97%9c%e5%ad%90%e6%9f%a5%e8%a9%a2%e7%9a%84%e6%80%a7%e8%83%bd-LLWaemRnuH\">4. \u76f8\u95dc\u5b50\u67e5\u8a62\u7684\u6027\u80fd<\/h3>\n<p>\u76f8\u95dc\u5b50\u67e5\u8a62\u5728\u6bcf\u6b21\u5916\u90e8\u67e5\u8a62\u57f7\u884c\u6642\u90fd\u6703\u88ab\u57f7\u884c\uff0c\u9019\u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u554f\u984c\u3002\u7576\u4f7f\u7528\u76f8\u95dc\u5b50\u67e5\u8a62\u6642\uff0c\u61c9\u8a72\u8b39\u614e\u8003\u616e\u5176\u5c0d\u6027\u80fd\u7684\u5f71\u97ff\uff0c\u4e26\u5728\u5fc5\u8981\u6642\u9032\u884c\u512a\u5316\u3002<\/p>\n<pre><code>SELECT e1.name FROM employees e1 WHERE e1.salary &gt; (SELECT AVG(salary) FROM employees e2 WHERE e1.department_id = e2.department_id);<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-LLWaemRnuH\">\u7e3d\u7d50<\/h2>\n<p>MySQL \u7684\u5b50\u67e5\u8a62\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u53ef\u4ee5\u5e6b\u52a9\u7528\u6236\u5728\u8907\u96dc\u7684\u67e5\u8a62\u4e2d\u7372\u53d6\u6240\u9700\u7684\u6578\u64da\u3002\u7136\u800c\uff0c\u5728\u4f7f\u7528\u5b50\u67e5\u8a62\u6642\uff0c\u5fc5\u9808\u8003\u616e\u6027\u80fd\u3001\u53ef\u8b80\u6027\u548c\u8fd4\u56de\u503c\u7684\u985e\u578b\u7b49\u56e0\u7d20\u3002\u901a\u904e\u5408\u7406\u4f7f\u7528\u5b50\u67e5\u8a62\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u63d0\u9ad8\u8cc7\u6599\u5eab\u64cd\u4f5c\u7684\u6548\u7387\u548c\u9748\u6d3b\u6027\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u9700\u6c42\u7684\u5ba2\u6236\u3002\u7121\u8ad6\u662f\u8cc7\u6599\u5eab\u7ba1\u7406\u9084\u662f\u7db2\u7ad9\u6258\u7ba1\uff0c\u6211\u5011\u7684 <a href=\"https:\/\/server.hk\">\u4f3a\u670d\u5668<\/a> \u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3MySQL\u5b50\u67e5\u8a62\u7684\u6ce8\u610f\u4e8b\u9805\uff0c\u63d0\u5347\u8cc7\u6599\u5eab\u64cd\u4f5c\u6548\u7387\uff0c\u907f\u514d\u5e38\u898b\u932f\u8aa4\uff0c\u512a\u5316\u67e5\u8a62\u6027\u80fd\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-160819","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160819","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=160819"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160819\/revisions"}],"predecessor-version":[{"id":160820,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160819\/revisions\/160820"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=160819"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=160819"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=160819"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}