{"id":200270,"date":"2025-05-06T09:44:43","date_gmt":"2025-05-06T01:44:43","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200270\/"},"modified":"2025-05-06T09:44:43","modified_gmt":"2025-05-06T01:44:43","slug":"%e5%a6%82%e4%bd%95%e7%a1%ae%e5%ae%9a-mysql-%e8%81%94%e5%90%88%e7%b4%a2%e5%bc%95%e4%b8%ad%e6%9f%a5%e8%af%a2%e6%b6%89%e5%8f%8a%e7%9a%84%e5%ad%97%e6%ae%b5%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200270\/","title":{"rendered":"\u5982\u4f55\u786e\u5b9a MySQL \u8054\u5408\u7d22\u5f15\u4e2d\u67e5\u8be2\u6d89\u53ca\u7684\u5b57\u6bb5\uff1f"},"content":{"rendered":"

<\/b> <\/p>\n

\u5982\u4f55\u786e\u5b9a MySQL \u8054\u5408\u7d22\u5f15\u4e2d\u67e5\u8be2\u6d89\u53ca\u7684\u5b57\u6bb5\uff1f<\/h1>\n

\u4eb2\u7231\u7684\u7f16\u7a0b\u5b66\u4e60\u7231\u597d\u8005\uff0c\u5982\u679c\u4f60\u70b9\u5f00\u4e86\u8fd9\u7bc7\u6587\u7ae0\uff0c\u8bf4\u660e\u4f60\u5bf9\u300a\u5982\u4f55\u786e\u5b9a MySQL \u8054\u5408\u7d22\u5f15\u4e2d\u67e5\u8be2\u6d89\u53ca\u7684\u5b57\u6bb5\uff1f\u300b\u5f88\u611f\u5174\u8da3\u3002\u672c\u7bc7\u6587\u7ae0\u5c31\u6765\u7ed9\u5927\u5bb6\u8be6\u7ec6\u89e3\u6790\u4e00\u4e0b\uff0c\u4e3b\u8981\u4ecb\u7ecd\u4e00\u4e0b\uff0c\u5e0c\u671b\u6240\u6709\u8ba4\u771f\u8bfb\u5b8c\u7684\u7ae5\u978b\u4eec\uff0c\u90fd\u6709\u5b9e\u8d28\u6027\u7684\u63d0\u9ad8\u3002<\/p>\n

<\/p>\n

\u5728\u8054\u5408\u7d22\u5f15\u4e2d\u5b9a\u4f4d\u67e5\u8be2\u6d89\u53ca\u7684\u5b57\u6bb5<\/strong><\/p>\n

\u5728 mysql \u4e2d\uff0c\u8054\u5408\u7d22\u5f15 a_b_c \u7531\u5b57\u6bb5 a\u3001b \u548c c \u7ec4\u6210\u3002\u8981\u786e\u5b9a\u67e5\u8be2\u6d89\u53ca\u4e86\u8054\u5408\u7d22\u5f15\u4e2d\u7684\u54ea\u4e9b\u5b57\u6bb5\uff0c\u9700\u8981\u4f7f\u7528\u4ee5\u4e0b\u6b65\u9aa4\uff1a<\/p>\n

    \n
  1. \u4f7f\u7528 explain \u5173\u952e\u5b57\u67e5\u770b\u6267\u884c\u8ba1\u5212<\/strong><\/li>\n<\/ol>\n

    \u4f7f\u7528\u4ee5\u4e0b\u67e5\u8be2\u67e5\u770b\u6267\u884c\u8ba1\u5212\uff1a<\/p>\n

    explain select * from test where a=10 and b>50;<\/pre>\n
      \n
    1. \u89e3\u8bfb\u6267\u884c\u8ba1\u5212<\/strong><\/li>\n<\/ol>\n
      \u6267\u884c\u8ba1\u5212\u4e2d\u5305\u542b\u4ee5\u4e0b\u5b57\u6bb5\uff1a<\/p>\n
        \n
      • extra<\/strong>\uff1a\u5305\u542b\u7d22\u5f15\u4f7f\u7528\u60c5\u51b5\u7684\u4fe1\u606f\u3002<\/li>\n
      • possible_keys<\/strong>\uff1a\u6570\u636e\u5e93\u53ef\u80fd\u4f7f\u7528\u7684\u7d22\u5f15\u3002<\/li>\n
      • key<\/strong>\uff1a\u5b9e\u9645\u4f7f\u7528\u7684\u7d22\u5f15\u3002<\/li>\n<\/ul>\n
          \n
        1. \u67e5\u627e key \u5b57\u6bb5<\/strong><\/li>\n<\/ol>\n
          \u5728 explain \u8f93\u51fa\u4e2d\u627e\u5230 key \u5b57\u6bb5\u3002\u8be5\u5b57\u6bb5\u5c06\u663e\u793a\u5b9e\u9645\u4f7f\u7528\u7684\u7d22\u5f15\uff0c\u5305\u62ec\u6240\u6d89\u53ca\u7684\u5b57\u6bb5\u3002\u4f8b\u5982\uff1a<\/p>\n
          key: a_b_c ((a,b))<\/pre>\n
          \u8fd9\u8868\u660e\u67e5\u8be2\u4f7f\u7528\u4e86 a_b_c \u7d22\u5f15\uff0c\u5e76\u4f7f\u7528\u4e86\u5176\u4e2d\u7684\u5b57\u6bb5 a \u548c b\u3002<\/p>\n
            \n
          1. \u91cd\u590d\u6b65\u9aa4 1-3<\/strong><\/li>\n<\/ol>\n
            \u5bf9\u6240\u6709\u5176\u4ed6\u67e5\u8be2\u91cd\u590d\u8fd9\u4e9b\u6b65\u9aa4\uff0c\u4ee5\u786e\u5b9a\u5b83\u4eec\u6d89\u53ca\u8054\u5408\u7d22\u5f15\u4e2d\u7684\u54ea\u4e9b\u5b57\u6bb5\u3002<\/p>\n
            \u672c\u7bc7\u5173\u4e8e\u300a\u5982\u4f55\u786e\u5b9a MySQL \u8054\u5408\u7d22\u5f15\u4e2d\u67e5\u8be2\u6d89\u53ca\u7684\u5b57\u6bb5\uff1f\u300b\u7684\u4ecb\u7ecd\u5c31\u5230\u6b64\u7ed3\u675f\u5566\uff0c\u4f46\u662f\u5b66\u65e0\u6b62\u5883\uff0c\u60f3\u8981\u4e86\u89e3\u5b66\u4e60\u66f4\u591a\u5173\u4e8e\u6570\u636e\u5e93\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u8bf7\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\uff01<\/p>\n
            \n
            \n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"
            \u5982\u4f55\u786e\u5b9a MySQL \u8054\u5408\u7d22\u5f15\u4e2d...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-200270","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200270","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=200270"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200270\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200270"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200270"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200270"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}