{"id":75632,"date":"2024-10-15T23:55:15","date_gmt":"2024-10-15T15:55:15","guid":{"rendered":"https:\/\/server.hk\/cnblog\/75632\/"},"modified":"2024-10-15T23:55:16","modified_gmt":"2024-10-15T15:55:16","slug":"mysql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%90%8c%e4%b8%80%e7%b5%90%e6%9e%9c%ef%bc%8c%e7%94%a8%e4%b8%8d%e5%90%8c%e5%91%bd%e4%bb%a4%e7%9a%84%e5%a4%a7%e5%b7%ae%e7%95%b0","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/75632\/","title":{"rendered":"MySQL \u6578\u64da\u5eab\u540c\u4e00\u7d50\u679c\uff0c\u7528\u4e0d\u540c\u547d\u4ee4\u7684\u5927\u5dee\u7570"},"content":{"rendered":"

MySQL \u6578\u64da\u5eab\u540c\u4e00\u7d50\u679c\uff0c\u7528\u4e0d\u540c\u547d\u4ee4\u7684\u5927\u5dee\u7570<\/h1>\n

\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0cMySQL \u662f\u4e00\u500b\u5ee3\u6cdb\u4f7f\u7528\u7684\u95dc\u806f\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u3002\u5b83\u63d0\u4f9b\u4e86\u591a\u7a2e\u547d\u4ee4\u4f86\u67e5\u8a62\u548c\u64cd\u4f5c\u6578\u64da\uff0c\u96d6\u7136\u9019\u4e9b\u547d\u4ee4\u53ef\u80fd\u6700\u7d42\u8fd4\u56de\u76f8\u540c\u7684\u7d50\u679c\uff0c\u4f46\u5b83\u5011\u5728\u6027\u80fd\u3001\u53ef\u8b80\u6027\u548c\u4f7f\u7528\u5834\u666f\u4e0a\u537b\u53ef\u80fd\u5b58\u5728\u986f\u8457\u5dee\u7570\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5e7e\u500b\u5e38\u898b\u7684 MySQL \u67e5\u8a62\u547d\u4ee4\uff0c\u4e26\u5206\u6790\u5b83\u5011\u4e4b\u9593\u7684\u5dee\u7570\u3002<\/p>\n

1. \u57fa\u672c\u67e5\u8a62\u547d\u4ee4<\/h2>\n

\u6700\u57fa\u672c\u7684\u67e5\u8a62\u547d\u4ee4\u662f SELECT<\/code>\u3002\u9019\u500b\u547d\u4ee4\u7528\u65bc\u5f9e\u6578\u64da\u8868\u4e2d\u6aa2\u7d22\u6578\u64da\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u67e5\u8a62\u793a\u4f8b\uff1a<\/p>\n

SELECT * FROM users WHERE age > 30;<\/code><\/pre>\n
\u9019\u689d\u547d\u4ee4\u5c07\u8fd4\u56de\u6240\u6709\u5e74\u9f61\u5927\u65bc 30 \u7684\u7528\u6236\u3002\u9019\u662f\u4e00\u500b\u76f4\u89c0\u4e14\u6613\u65bc\u7406\u89e3\u7684\u67e5\u8a62\uff0c\u4f46\u5728\u6578\u64da\u91cf\u9f90\u5927\u7684\u60c5\u6cc1\u4e0b\uff0c\u6027\u80fd\u53ef\u80fd\u6703\u53d7\u5230\u5f71\u97ff\u3002<\/p>\n
2. \u4f7f\u7528\u7d22\u5f15\u7684\u67e5\u8a62<\/h2>\n
\u70ba\u4e86\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\uff0cMySQL \u63d0\u4f9b\u4e86\u7d22\u5f15\u529f\u80fd\u3002\u7576\u6211\u5011\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u7d22\u5f15\u6642\uff0c\u67e5\u8a62\u7684\u901f\u5ea6\u6703\u986f\u8457\u63d0\u9ad8\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT * FROM users USE INDEX (age_index) WHERE age > 30;<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0cUSE INDEX<\/code> \u547d\u4ee4\u544a\u8a34 MySQL \u4f7f\u7528\u540d\u70ba age_index<\/code> \u7684\u7d22\u5f15\u4f86\u52a0\u901f\u67e5\u8a62\u3002\u9019\u6a23\u7684\u67e5\u8a62\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\uff0c\u6027\u80fd\u6703\u66f4\u4f73\u3002<\/p>\n
3. \u805a\u5408\u51fd\u6578\u7684\u4f7f\u7528<\/h2>\n
\u805a\u5408\u51fd\u6578\u5982 COUNT<\/code>\u3001SUM<\/code> \u548c AVG<\/code> \u53ef\u4ee5\u7528\u4f86\u5c0d\u6578\u64da\u9032\u884c\u7d71\u8a08\u5206\u6790\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT COUNT(*) FROM users WHERE age > 30;<\/code><\/pre>\n
\u9019\u689d\u547d\u4ee4\u5c07\u8fd4\u56de\u5e74\u9f61\u5927\u65bc 30 \u7684\u7528\u6236\u6578\u91cf\u3002\u4f7f\u7528\u805a\u5408\u51fd\u6578\u53ef\u4ee5\u7c21\u5316\u67e5\u8a62\u7d50\u679c\uff0c\u4e26\u63d0\u4f9b\u6709\u7528\u7684\u7d71\u8a08\u4fe1\u606f\u3002<\/p>\n
4. \u5b50\u67e5\u8a62\u8207\u806f\u63a5<\/h2>\n
\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528\u5b50\u67e5\u8a62\u6216\u806f\u63a5\u53ef\u4ee5\u7372\u5f97\u66f4\u9748\u6d3b\u7684\u67e5\u8a62\u7d50\u679c\u3002\u4f8b\u5982\uff0c\u4f7f\u7528\u806f\u63a5\u4f86\u7372\u53d6\u7528\u6236\u53ca\u5176\u8a02\u55ae\u4fe1\u606f\uff1a<\/p>\n
SELECT users.name, orders.amount \nFROM users \nJOIN orders ON users.id = orders.user_id \nWHERE users.age > 30;<\/code><\/pre>\n
\u9019\u689d\u547d\u4ee4\u5c07\u8fd4\u56de\u6240\u6709\u5e74\u9f61\u5927\u65bc 30 \u7684\u7528\u6236\u53ca\u5176\u8a02\u55ae\u91d1\u984d\u3002\u806f\u63a5\u67e5\u8a62\u901a\u5e38\u6bd4\u5b50\u67e5\u8a62\u66f4\u9ad8\u6548\uff0c\u56e0\u70ba\u5b83\u5011\u53ef\u4ee5\u5728\u55ae\u4e00\u67e5\u8a62\u4e2d\u7372\u53d6\u6240\u9700\u7684\u6240\u6709\u6578\u64da\u3002<\/p>\n
5. \u6027\u80fd\u8003\u91cf<\/h2>\n
\u96d6\u7136\u4e0d\u540c\u7684\u67e5\u8a62\u547d\u4ee4\u53ef\u80fd\u8fd4\u56de\u76f8\u540c\u7684\u7d50\u679c\uff0c\u4f46\u5b83\u5011\u7684\u6027\u80fd\u5dee\u7570\u537b\u4e0d\u5bb9\u5ffd\u8996\u3002\u4f7f\u7528\u7d22\u5f15\u3001\u805a\u5408\u51fd\u6578\u548c\u806f\u63a5\u53ef\u4ee5\u986f\u8457\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002\u5728\u8a2d\u8a08\u6578\u64da\u5eab\u548c\u64b0\u5beb\u67e5\u8a62\u6642\uff0c\u958b\u767c\u8005\u61c9\u8003\u616e\u5230\u9019\u4e9b\u56e0\u7d20\uff0c\u4ee5\u78ba\u4fdd\u7cfb\u7d71\u7684\u9ad8\u6548\u904b\u884c\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
\u5728 MySQL \u6578\u64da\u5eab\u4e2d\uff0c\u96d6\u7136\u4e0d\u540c\u7684\u67e5\u8a62\u547d\u4ee4\u53ef\u80fd\u6700\u7d42\u8fd4\u56de\u76f8\u540c\u7684\u7d50\u679c\uff0c\u4f46\u5b83\u5011\u5728\u6027\u80fd\u548c\u53ef\u8b80\u6027\u4e0a\u5b58\u5728\u986f\u8457\u5dee\u7570\u3002\u4e86\u89e3\u9019\u4e9b\u5dee\u7570\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u64b0\u5beb\u66f4\u9ad8\u6548\u7684\u67e5\u8a62\uff0c\u5f9e\u800c\u63d0\u5347\u61c9\u7528\u7a0b\u5e8f\u7684\u6574\u9ad4\u6027\u80fd\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u7528\u6236\uff0c\u9078\u64c7\u5408\u9069\u7684 VPS<\/a> \u89e3\u6c7a\u65b9\u6848\u4e5f\u662f\u81f3\u95dc\u91cd\u8981\u7684\uff0c\u9019\u6a23\u53ef\u4ee5\u78ba\u4fdd\u6578\u64da\u5eab\u7684\u7a69\u5b9a\u6027\u548c\u5feb\u901f\u97ff\u61c9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u63a2\u7d22 MySQL \u6578\u64da\u5eab\u4e2d\u4f7f\u7528\u4e0d\u540c\u547d\u4ee4\u7372\u53d6\u76f8\u540c\u7d50\u679c\u7684\u986f\u8457\u5dee\u7570\uff0c\u4e86\u89e3\u6027\u80fd\u8207\u6548\u7387\u7684\u5f71\u97ff\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-75632","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/75632","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=75632"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/75632\/revisions"}],"predecessor-version":[{"id":75633,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/75632\/revisions\/75633"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=75632"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=75632"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=75632"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}