{"id":77554,"date":"2024-10-16T10:51:17","date_gmt":"2024-10-16T02:51:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/77554\/"},"modified":"2024-10-16T10:51:17","modified_gmt":"2024-10-16T02:51:17","slug":"mysql%e6%ba%90%e7%a2%bc%e8%a7%a3%e6%9e%90%e4%b9%8b%e5%9f%b7%e8%a1%8c%e8%a8%88%e5%8a%83","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/77554\/","title":{"rendered":"MySQL\u6e90\u78bc\u89e3\u6790\u4e4b\u57f7\u884c\u8a08\u5283"},"content":{"rendered":"<h1 id=\"mysql%e6%ba%90%e7%a2%bc%e8%a7%a3%e6%9e%90%e4%b9%8b%e5%9f%b7%e8%a1%8c%e8%a8%88%e5%8a%83-VXaWNncCBe\">MySQL\u6e90\u78bc\u89e3\u6790\u4e4b\u57f7\u884c\u8a08\u5283<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cMySQL\u662f\u4e00\u500b\u5ee3\u6cdb\u4f7f\u7528\u7684\u958b\u6e90\u95dc\u4fc2\u578b\u6578\u64da\u5eab\u3002\u7406\u89e3MySQL\u7684\u57f7\u884c\u8a08\u5283\u5c0d\u65bc\u512a\u5316\u67e5\u8a62\u6027\u80fd\u81f3\u95dc\u91cd\u8981\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eMySQL\u7684\u57f7\u884c\u8a08\u5283\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u66f4\u597d\u5730\u7406\u89e3\u5176\u904b\u4f5c\u539f\u7406\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af%e5%9f%b7%e8%a1%8c%e8%a8%88%e5%8a%83%ef%bc%9f-VXaWNncCBe\">\u4ec0\u9ebc\u662f\u57f7\u884c\u8a08\u5283\uff1f<\/h2>\n<p>\u57f7\u884c\u8a08\u5283\u662f\u6578\u64da\u5eab\u7cfb\u7d71\u5728\u57f7\u884cSQL\u67e5\u8a62\u6642\u6240\u63a1\u7528\u7684\u6b65\u9a5f\u548c\u7b56\u7565\u3002\u5b83\u63cf\u8ff0\u4e86\u6578\u64da\u5eab\u5982\u4f55\u8a2a\u554f\u6578\u64da\uff0c\u5305\u62ec\u4f7f\u7528\u7684\u7d22\u5f15\u3001\u8868\u7684\u9023\u63a5\u65b9\u5f0f\u4ee5\u53ca\u6578\u64da\u7684\u904e\u6ffe\u548c\u6392\u5e8f\u7b49\u3002\u901a\u904e\u5206\u6790\u57f7\u884c\u8a08\u5283\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u8b58\u5225\u6027\u80fd\u74f6\u9838\uff0c\u4e26\u9032\u884c\u76f8\u61c9\u7684\u512a\u5316\u3002<\/p>\n<h2 id=\"%e5%a6%82%e4%bd%95%e7%8d%b2%e5%8f%96%e5%9f%b7%e8%a1%8c%e8%a8%88%e5%8a%83-VXaWNncCBe\">\u5982\u4f55\u7372\u53d6\u57f7\u884c\u8a08\u5283<\/h2>\n<p>\u5728MySQL\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528EXPLAIN\u8a9e\u53e5\u4f86\u7372\u53d6\u67e5\u8a62\u7684\u57f7\u884c\u8a08\u5283\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>EXPLAIN SELECT * FROM users WHERE age &gt; 30;<\/code><\/pre>\n<p>\u57f7\u884c\u4e0a\u8ff0\u8a9e\u53e5\u5f8c\uff0cMySQL\u5c07\u8fd4\u56de\u4e00\u500b\u8868\u683c\uff0c\u986f\u793a\u67e5\u8a62\u7684\u57f7\u884c\u8a08\u5283\u3002\u9019\u500b\u8868\u683c\u901a\u5e38\u5305\u542b\u4ee5\u4e0b\u5e7e\u500b\u91cd\u8981\u5b57\u6bb5\uff1a<\/p>\n<ul>\n<li><strong>id<\/strong>\uff1a\u67e5\u8a62\u7684\u552f\u4e00\u6a19\u8b58\u7b26\u3002<\/li>\n<li><strong>select_type<\/strong>\uff1a\u67e5\u8a62\u7684\u985e\u578b\uff0c\u4f8b\u5982\u7c21\u55ae\u67e5\u8a62\u6216\u806f\u5408\u67e5\u8a62\u3002<\/li>\n<li><strong>table<\/strong>\uff1a\u6b63\u5728\u8a2a\u554f\u7684\u8868\u540d\u3002<\/li>\n<li><strong>type<\/strong>\uff1a\u9023\u63a5\u985e\u578b\uff0c\u986f\u793a\u6578\u64da\u8a2a\u554f\u7684\u6548\u7387\u3002<\/li>\n<li><strong>possible_keys<\/strong>\uff1a\u53ef\u80fd\u4f7f\u7528\u7684\u7d22\u5f15\u3002<\/li>\n<li><strong>key<\/strong>\uff1a\u5be6\u969b\u4f7f\u7528\u7684\u7d22\u5f15\u3002<\/li>\n<li><strong>rows<\/strong>\uff1a\u9810\u4f30\u9700\u8981\u6383\u63cf\u7684\u884c\u6578\u3002<\/li>\n<li><strong>Extra<\/strong>\uff1a\u5176\u4ed6\u4fe1\u606f\uff0c\u4f8b\u5982\u662f\u5426\u4f7f\u7528\u4e86\u81e8\u6642\u8868\u6216\u6587\u4ef6\u6392\u5e8f\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%9f%b7%e8%a1%8c%e8%a8%88%e5%8a%83%e7%9a%84%e5%88%86%e6%9e%90-VXaWNncCBe\">\u57f7\u884c\u8a08\u5283\u7684\u5206\u6790<\/h2>\n<p>\u5728\u7372\u53d6\u57f7\u884c\u8a08\u5283\u5f8c\uff0c\u958b\u767c\u8005\u9700\u8981\u5c0d\u5176\u9032\u884c\u5206\u6790\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u5206\u6790\u65b9\u6cd5\uff1a<\/p>\n<h3 id=\"1-%e9%80%a3%e6%8e%a5%e9%a1%9e%e5%9e%8b-VXaWNncCBe\">1. \u9023\u63a5\u985e\u578b<\/h3>\n<p>\u9023\u63a5\u985e\u578b\u662f\u8a55\u4f30\u67e5\u8a62\u6027\u80fd\u7684\u95dc\u9375\u6307\u6a19\u3002\u5e38\u898b\u7684\u9023\u63a5\u985e\u578b\u5305\u62ec\uff1a<\/p>\n<ul>\n<li><strong>ALL<\/strong>\uff1a\u5168\u8868\u6383\u63cf\uff0c\u6548\u7387\u6700\u4f4e\u3002<\/li>\n<li><strong>index<\/strong>\uff1a\u7d22\u5f15\u6383\u63cf\uff0c\u6548\u7387\u8f03\u9ad8\u3002<\/li>\n<li><strong>range<\/strong>\uff1a\u7bc4\u570d\u6383\u63cf\uff0c\u9069\u5408\u67e5\u8a62\u7bc4\u570d\u5167\u7684\u6578\u64da\u3002<\/li>\n<li><strong>ref<\/strong>\uff1a\u4f7f\u7528\u975e\u552f\u4e00\u7d22\u5f15\uff0c\u6548\u7387\u8f03\u9ad8\u3002<\/li>\n<li><strong>eq_ref<\/strong>\uff1a\u4f7f\u7528\u552f\u4e00\u7d22\u5f15\uff0c\u6548\u7387\u6700\u9ad8\u3002<\/li>\n<\/ul>\n<h3 id=\"2-%e4%bd%bf%e7%94%a8%e7%b4%a2%e5%bc%95-VXaWNncCBe\">2. \u4f7f\u7528\u7d22\u5f15<\/h3>\n<p>\u7d22\u5f15\u7684\u4f7f\u7528\u5c0d\u67e5\u8a62\u6027\u80fd\u5f71\u97ff\u91cd\u5927\u3002\u7576<code>possible_keys<\/code>\u4e2d\u6709\u7d22\u5f15\u4f46<code>key<\/code>\u70baNULL\u6642\uff0c\u8868\u793a\u67e5\u8a62\u672a\u80fd\u6709\u6548\u5229\u7528\u7d22\u5f15\u3002\u9019\u6642\u53ef\u4ee5\u8003\u616e\u6dfb\u52a0\u6216\u8abf\u6574\u7d22\u5f15\u3002<\/p>\n<h3 id=\"3-%e9%a0%90%e4%bc%b0%e8%a1%8c%e6%95%b8-VXaWNncCBe\">3. \u9810\u4f30\u884c\u6578<\/h3>\n<p>\u9810\u4f30\u7684\u884c\u6578\uff08<code>rows<\/code>\uff09\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u4e86\u89e3\u67e5\u8a62\u7684\u8907\u96dc\u6027\u3002\u5982\u679c\u9810\u4f30\u7684\u884c\u6578\u904e\u9ad8\uff0c\u53ef\u80fd\u9700\u8981\u91cd\u65b0\u8a2d\u8a08\u67e5\u8a62\u6216\u6578\u64da\u7d50\u69cb\u3002<\/p>\n<h2 id=\"%e5%84%aa%e5%8c%96%e5%9f%b7%e8%a1%8c%e8%a8%88%e5%8a%83-VXaWNncCBe\">\u512a\u5316\u57f7\u884c\u8a08\u5283<\/h2>\n<p>\u6839\u64da\u57f7\u884c\u8a08\u5283\u7684\u5206\u6790\u7d50\u679c\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u63a1\u53d6\u4ee5\u4e0b\u512a\u5316\u63aa\u65bd\uff1a<\/p>\n<ul>\n<li>\u6dfb\u52a0\u6216\u8abf\u6574\u7d22\u5f15\u4ee5\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/li>\n<li>\u91cd\u69cb\u67e5\u8a62\u8a9e\u53e5\uff0c\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u5168\u8868\u6383\u63cf\u3002<\/li>\n<li>\u4f7f\u7528JOIN\u800c\u975e\u5b50\u67e5\u8a62\uff0c\u901a\u5e38\u80fd\u63d0\u9ad8\u6027\u80fd\u3002<\/li>\n<li>\u5b9a\u671f\u66f4\u65b0\u7d71\u8a08\u4fe1\u606f\uff0c\u4ee5\u5e6b\u52a9MySQL\u751f\u6210\u66f4\u512a\u7684\u57f7\u884c\u8a08\u5283\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-VXaWNncCBe\">\u7e3d\u7d50<\/h2>\n<p>\u7406\u89e3MySQL\u7684\u57f7\u884c\u8a08\u5283\u662f\u6578\u64da\u5eab\u6027\u80fd\u512a\u5316\u7684\u91cd\u8981\u6b65\u9a5f\u3002\u901a\u904e\u4f7f\u7528EXPLAIN\u8a9e\u53e5\u7372\u53d6\u57f7\u884c\u8a08\u5283\uff0c\u4e26\u5c0d\u5176\u9032\u884c\u6df1\u5165\u5206\u6790\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u8b58\u5225\u6027\u80fd\u74f6\u9838\u4e26\u9032\u884c\u76f8\u61c9\u7684\u512a\u5316\u3002\u9019\u4e0d\u50c5\u80fd\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\uff0c\u9084\u80fd\u63d0\u5347\u6574\u9ad4\u7cfb\u7d71\u7684\u6027\u80fd\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528\u6211\u5011\u7684<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u670d\u52d9\uff0c\u70ba\u60a8\u7684\u61c9\u7528\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6df1\u5165\u89e3\u6790MySQL\u6e90\u78bc\u4e2d\u7684\u57f7\u884c\u8a08\u5283\uff0c\u63ed\u793a\u67e5\u8a62\u512a\u5316\u904e\u7a0b\u53ca\u5176\u80cc\u5f8c\u7684\u539f\u7406\uff0c\u52a9\u529b\u6578\u64da\u5eab\u6027\u80fd\u63d0\u5347\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-77554","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/77554","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=77554"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/77554\/revisions"}],"predecessor-version":[{"id":77555,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/77554\/revisions\/77555"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=77554"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=77554"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=77554"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}