{"id":200143,"date":"2025-05-06T10:46:32","date_gmt":"2025-05-06T02:46:32","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200143\/"},"modified":"2025-05-06T10:46:32","modified_gmt":"2025-05-06T02:46:32","slug":"sql%ef%bc%9a%e7%bb%93%e6%9e%84%e5%8c%96%e6%9f%a5%e8%af%a2%e8%af%ad%e8%a8%80%e7%ae%80%e4%bb%8b","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200143\/","title":{"rendered":"SQL\uff1a\u7ed3\u6784\u5316\u67e5\u8be2\u8bed\u8a00\u7b80\u4ecb"},"content":{"rendered":"

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

SQL\uff1a\u7ed3\u6784\u5316\u67e5\u8be2\u8bed\u8a00\u7b80\u4ecb<\/h1>\n

\u4e3b\u673a\u5b9d\u8d1d\u4eca\u5929\u5c06\u7ed9\u5927\u5bb6\u5e26\u6765\uff0c\u611f\u5174\u8da3\u7684\u670b\u53cb\u8bf7\u7ee7\u7eed\u770b\u4e0b\u53bb\u5427\uff01\u4ee5\u4e0b\u5185\u5bb9\u5c06\u4f1a\u6d89\u53ca\u5230\u7b49\u7b49\u77e5\u8bc6\u70b9\uff0c\u5982\u679c\u4f60\u662f\u6b63\u5728\u5b66\u4e60\u6216\u8005\u5df2\u7ecf\u662f\u5927\u4f6c\u7ea7\u522b\u4e86\uff0c\u90fd\u975e\u5e38\u6b22\u8fce\u4e5f\u5e0c\u671b\u5927\u5bb6\u90fd\u80fd\u7ed9\u6211\u5efa\u8bae\u8bc4\u8bba\u54c8~\u5e0c\u671b\u80fd\u5e2e\u52a9\u5230\u5927\u5bb6\uff01<\/p>\n

<\/p>\n

\u6982\u8ff0<\/strong> sql \u662f\u4efb\u4f55\u6570\u636e\u5e93\u7ba1\u7406\u548c\u64cd\u4f5c\u7684\u652f\u67f1\u3002\u5b83\u662f\u4e00\u79cd\u9002\u5408\u4e0e\u5173\u7cfb\u6570\u636e\u5e93\u4ea4\u4e92\u7684\u8bed\u8a00\u3002\u5373\u4f7f\u6d89\u53ca\u5c11\u91cf\u4fe1\u606f\u6216\u6d77\u91cf\u6570\u636e\uff0csql \u4e5f\u662f\u7f16\u7a0b\u4e2d\u9996\u9009\u7684\u57fa\u672c\u6280\u80fd\u4e4b\u4e00\u3002\u672c\u6559\u7a0b\u5c06\u4ecb\u7ecd sql \u7684\u57fa\u7840\u77e5\u8bc6\u53ca\u5176\u5728\u65b0\u6280\u672f\u4e2d\u9700\u8981\u8003\u8651\u7684\u6700\u91cd\u8981\u7684\u547d\u4ee4\u3002<\/p>\n

\u4ec0\u4e48\u662f sql\uff1f <\/h2>\n

sql \u6210\u4e3a\u4e0e\u6570\u636e\u5e93\u901a\u4fe1\u7684\u6807\u51c6\u5316\u8bed\u8a00\u3002\u5176\u4e3b\u8981\u76ee\u7684\u662f\u67e5\u8be2\u3001\u66f4\u65b0\u548c\u7ba1\u7406\u6570\u636e\u3002\u5927\u591a\u6570\u73b0\u4ee3\u6570\u636e\u5e93\uff0c\u4f8b\u5982 mysql\u3001postgresql\u3001oracle \u548c sql server\uff0c\u90fd\u4f7f\u7528 sql \u4f5c\u4e3a\u67e5\u8be2\u8bed\u8a00\u3002<\/p>\n

sql \u4e2d\u7684\u5173\u952e\u6982\u5ff5 <\/h2>\n

\u5173\u7cfb\u6570\u636e\u5e93 <\/h2>\n

sql\u64cd\u4f5c\u6d89\u53ca\u5173\u7cfb\u6570\u636e\u5e93\u7684\u6570\u636e\u3002\u5173\u7cfb\u6570\u636e\u5e93\u4ee5\u8868\u7684\u5f62\u5f0f\u5b58\u50a8\u6570\u636e\uff0c\u8868\u7531\u884c\u548c\u5217\u7ec4\u6210\u3002\u8fd9\u4e9b\u8868\u901a\u8fc7\u5173\u7cfb\u76f8\u4e92\u5173\u8054\uff1a\u4e00\u5bf9\u4e00\u3001\u4e00\u5bf9\u591a\u6216\u591a\u5bf9\u591a\u3002<\/p>\n

\u6570\u636e\u7c7b\u578b <\/h2>\n

sql \u63d0\u4f9b\u5404\u79cd\u6570\u636e\u7c7b\u578b\uff0c\u5982 int\u3001varchar\u3001date \u548c boolean \u6765\u63cf\u8ff0\u4e00\u5217\u4e2d\u4efb\u4f55\u6570\u636e\u7684\u6027\u8d28\u3002<\/p>\n

\u6b63\u5e38\u5316 <\/h2>\n

\u6807\u51c6\u5316\u662f\u6700\u5c0f\u5316\u5197\u4f59\u7684\u6570\u636e\u7ec4\u7ec7\u6280\u672f\u3002\u5927\u591a\u6570 sql \u67e5\u8be2\u90fd\u4f9d\u8d56\u4e8e\u89c4\u8303\u5316\u8868\uff0c\u4ee5\u4fbf\u9ad8\u6548\u6267\u884c\u5e76\u4f7f\u6570\u636e\u64cd\u4f5c\u66f4\u5bb9\u6613\u3002<\/p>\n

\u57fa\u672c sql \u547d\u4ee4 <\/h2>\n

**<\/p>\n

    \n
  1. \u9009\u62e9 ** select \u8bed\u53e5\u662f\u6700\u5e38\u7528\u7684 sql \u547d\u4ee4\u3002\u5b83\u4ece\u6570\u636e\u5e93\u68c0\u7d22\u6570\u636e\u3002<\/li>\n<\/ol>\n

    `\u4ece\u8868\u540d\u4e2d\u9009\u62e9\u5217 1\u3001\u5217 2\uff1b<\/p>\n

    \u4ece\u7528\u6237\u4e2d\u9009\u62e9\u59d3\u540d\u3001\u5e74\u9f84\uff1b`<\/p>\n

    2\u3002\u63d2\u5165<\/strong>
    insert \u547d\u4ee4\u5c06\u65b0\u8bb0\u5f55\u6dfb\u52a0\u5230\u8868\u4e2d\u3002<\/p>\n

    insert into table_name (column1, column2) values (value1, value2);
    \u793a\u4f8b\uff1a<\/p>\n

    insert into users (name, age) values ('alice', 30);\n<\/pre>\n
    **<\/p>\n
      \n
    1. \u66f4\u65b0 ** update \u547d\u4ee4\u4fee\u6539\u8868\u4e2d\u7684\u73b0\u6709\u8bb0\u5f55\u3002<\/li>\n<\/ol>\n
      update table_name set column1 = value1 where \u6761\u4ef6;
       \u793a\u4f8b\uff1a<\/p>\n
      **<\/p>\n
        \n
      1. \u66f4\u65b0\u7528\u6237 set \u5e74\u9f84 = 31 where name = ‘alice’; ** \u5220\u9664 delete \u547d\u4ee4\u4ece\u8868\u4e2d\u5220\u9664\u8bb0\u5f55\u3002<\/li>\n<\/ol>\n
        delete from table_name where \u6761\u4ef6\uff1b
         \u793a\u4f8b\uff1a<\/p>\n
        \u4ece\u5e74\u9f84\u4e3a < 18 \u7684\u7528\u6237\u4e2d\u5220\u9664\uff1b
         **<\/p>\n
          \n
        1. \u521b\u5efa\u8868 ** create table \u8bed\u53e5\u7528\u4e8e\u5728\u6570\u636e\u5e93\u4e2d\u521b\u5efa\u4e00\u4e2a\u65b0\u8868\u3002<\/li>\n<\/ol>\n
          create table \u8868\u540d\uff08\u5217 1 \u6570\u636e\u7c7b\u578b\uff0c\u5217 2 \u6570\u636e\u7c7b\u578b\uff09;
           \u793a\u4f8b\uff1a<\/p>\n
          \u521b\u5efa\u8868\u5458\u5de5\uff08id int\uff0c\u59d3\u540d varchar(100)\uff0c\u804c\u4f4d varchar(100));<\/p>\n
          **<\/p>\n
           \u67e5\u8be2\u6570\u636e <\/h2>\n
          **
           where \u5b50\u53e5\u5bf9\u4e8e\u8fc7\u6ee4\u7ed3\u679c\u81f3\u5173\u91cd\u8981\u3002\u60a8\u53ef\u4ee5\u4f7f\u7528 and\u3001or \u548c not \u7b49\u903b\u8f91\u8fd0\u7b97\u7b26\u7ec4\u5408\u6761\u4ef6\u3002<\/p>\n
          \u4ece\u5458\u5de5\u4e2d\u9009\u62e9*\uff0c\u5176\u4e2d\u804c\u4f4d = ‘\u7ecf\u7406’\u5e76\u4e14\u5e74\u9f84 > 30;
          \u8fde\u63a5\u8868<\/strong>
           \u8fde\u63a5\u5141\u8bb8 sql \u67e5\u8be2\u6839\u636e\u76f8\u5173\u5217\u7ec4\u5408\u6765\u81ea\u591a\u4e2a\u8868\u7684\u6570\u636e\u3002<\/p>\n
          inner join \u68c0\u7d22\u4e24\u4e2a\u8868\u4e2d\u5177\u6709\u5339\u914d\u503c\u7684\u8bb0\u5f55\u3002<\/p>\n
          select employees.name, departments.department_name \nfrom employees\ninner join departments on employees.department_id = departments.id;\n<\/pre>\n
          left join<\/strong> \u68c0\u7d22\u5de6\u8868\u4e2d\u7684\u6240\u6709\u8bb0\u5f55\u4ee5\u53ca\u53f3\u8868\u4e2d\u7684\u5339\u914d\u8bb0\u5f55\u3002<\/p>\n
          SELECT employees.name, departments.department_name \nFROM employees\nLEFT JOIN departments ON employees.department_id = departments.id;\n<\/pre>\n
           \u9ad8\u7ea7 sql \u529f\u80fd <\/h2>\n
          \u7d22\u5f15
           \u7d22\u5f15\u901a\u8fc7\u5141\u8bb8\u66f4\u5feb\u5730\u68c0\u7d22\u8bb0\u5f55\u6765\u63d0\u9ad8\u67e5\u8be2\u6027\u80fd\u3002<\/p>\n
          create index index_name on table_name (column_name);
          \u805a\u5408\u51fd\u6570<\/strong>
           count()\u3001sum() \u548c avg() \u7b49\u51fd\u6570\u5141\u8bb8\u60a8\u5bf9\u6570\u636e\u6267\u884c\u8ba1\u7b97\u3002<\/p>\n
          \u4ece\u5e74\u9f84\u4e3a > 30 \u7684\u7528\u6237\u4e2d\u9009\u62e9 count(*) \u4e2a\uff1b
          \u5b50\u67e5\u8be2<\/strong>
           \u5b50\u67e5\u8be2\u662f\u53e6\u4e00\u4e2a\u67e5\u8be2\u4e2d\u7684\u67e5\u8be2\uff0c\u901a\u5e38\u7528\u4e8e\u5728\u590d\u6742\u64cd\u4f5c\u4e2d\u8fc7\u6ee4\u6570\u636e\u3002<\/p>\n
          \u4ece\u7528\u6237\u4e2d\u9009\u62e9\u59d3\u540d\uff0c\u5176\u4e2d\u5e74\u9f84 = (select max(\u5e74\u9f84) from \u7528\u6237);<\/p>\n
           \u7ed3\u8bba <\/h2>\n
          sql \u662f\u5927\u591a\u6570\u5e94\u7528\u7a0b\u5e8f\u6570\u636e\u7ba1\u7406\u7684\u652f\u67f1\uff1b\u56e0\u6b64\uff0c\u5b83\u5bf9\u4e8e\u5f00\u53d1\u4eba\u5458\u3001\u6570\u636e\u5206\u6790\u5e08\u548c\u6570\u636e\u5e93\u7ba1\u7406\u5458\u6765\u8bf4\u662f\u975e\u5e38\u91cd\u8981\u7684\u5f00\u53d1\u5de5\u5177\u3002\u5b66\u4e60 sql \u7684\u57fa\u7840\u77e5\u8bc6\uff08\u4ece\u67e5\u8be2\u5230\u63d2\u5165\u3001\u66f4\u65b0\u548c\u5220\u9664\u6570\u636e\uff09\u4e3a\u66f4\u6df1\u5165\u5730\u63a2\u7d22 dbms \u5960\u5b9a\u4e86\u57fa\u7840\u3002<\/p>\n
          \u7ec8\u4e8e\u4ecb\u7ecd\u5b8c\u5566\uff01\u5c0f\u4f19\u4f34\u4eec\uff0c\u8fd9\u7bc7\u5173\u4e8e\u300aSQL\uff1a\u7ed3\u6784\u5316\u67e5\u8be2\u8bed\u8a00\u7b80\u4ecb\u300b\u7684\u4ecb\u7ecd\u5e94\u8be5\u8ba9\u4f60\u6536\u83b7\u591a\u591a\u4e86\u5427\uff01\u6b22\u8fce\u5927\u5bb6\u6536\u85cf\u6216\u5206\u4eab\u7ed9\u66f4\u591a\u9700\u8981\u5b66\u4e60\u7684\u670b\u53cb\u5427~\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u4e5f\u4f1a\u53d1\u5e03\u6570\u636e\u5e93\u76f8\u5173\u77e5\u8bc6\uff0c\u5feb\u6765\u5173\u6ce8\u5427\uff01<\/p>\n
           \u7248\u672c\u58f0\u660e \u672c\u6587\u8f6c\u8f7d\u4e8e\uff1adev.to \u5982\u6709\u4fb5\u72af\uff0c\u8bf7\u8054\u7cfb \u5220\u9664 <\/p>\n
          \n
          \n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"
          SQL\uff1a\u7ed3\u6784\u5316\u67e5\u8be2\u8bed\u8a00\u7b80\u4ecb \u4e3b\u673a...<\/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-200143","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200143","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=200143"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200143\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200143"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200143"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200143"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}