{"id":168429,"date":"2024-11-06T12:18:22","date_gmt":"2024-11-06T04:18:22","guid":{"rendered":"https:\/\/server.hk\/cnblog\/168429\/"},"modified":"2024-11-06T12:18:23","modified_gmt":"2024-11-06T04:18:23","slug":"sql-%e6%9c%89%e5%ba%8f%e8%99%9f%e8%a1%a8%e9%80%a3%e6%8e%a5%ef%bc%8c%e5%a6%82%e4%bd%95%e6%8f%90%e9%ab%98%e6%95%b8%e6%93%9a%e5%ba%ab%e6%9f%a5%e8%a9%a2%e6%95%88%e7%8e%87%ef%bc%9f-sql-%e6%9c%89%e5%ba%8f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/168429\/","title":{"rendered":"SQL \u6709\u5e8f\u865f\u8868\u9023\u63a5\uff0c\u5982\u4f55\u63d0\u9ad8\u6578\u64da\u5eab\u67e5\u8a62\u6548\u7387\uff1f (sql \u6709\u5e8f\u865f\u6578\u64da\u5eab\u8868\u9023\u63a5)"},"content":{"rendered":"

SQL \u6709\u5e8f\u865f\u8868\u9023\u63a5\uff0c\u5982\u4f55\u63d0\u9ad8\u6578\u64da\u5eab\u67e5\u8a62\u6548\u7387\uff1f<\/h1>\n

\u5728\u73fe\u4eca\u7684\u6578\u64da\u9a45\u52d5\u6642\u4ee3\uff0c\u6578\u64da\u5eab\u7684\u67e5\u8a62\u6548\u7387\u5c0d\u65bc\u61c9\u7528\u7a0b\u5e8f\u7684\u6027\u80fd\u81f3\u95dc\u91cd\u8981\u3002\u5c24\u5176\u662f\u5728\u8655\u7406\u6709\u5e8f\u865f\u8868\u9023\u63a5\u6642\uff0c\u5982\u4f55\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u6210\u70ba\u4e86\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u9700\u8981\u9762\u5c0d\u7684\u4e00\u500b\u6311\u6230\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u6709\u5e8f\u865f\u8868\u9023\u63a5\u7684\u6982\u5ff5\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u7684\u5be6\u7528\u6280\u5de7\u3002<\/p>\n

\u4ec0\u9ebc\u662f\u6709\u5e8f\u865f\u8868\u9023\u63a5\uff1f<\/h2>\n

\u6709\u5e8f\u865f\u8868\u9023\u63a5\u662f\u6307\u5728 SQL \u67e5\u8a62\u4e2d\uff0c\u901a\u904e\u67d0\u500b\u7279\u5b9a\u7684\u6b04\u4f4d\uff08\u901a\u5e38\u662f\u4e3b\u9375\u6216\u7d22\u5f15\uff09\u5c07\u5169\u500b\u6216\u591a\u500b\u8868\u9032\u884c\u9023\u63a5\u3002\u9019\u7a2e\u9023\u63a5\u65b9\u5f0f\u901a\u5e38\u7528\u65bc\u9700\u8981\u5f9e\u591a\u500b\u8868\u4e2d\u63d0\u53d6\u76f8\u95dc\u6578\u64da\u7684\u60c5\u6cc1\u3002\u8209\u4f8b\u4f86\u8aaa\uff0c\u5047\u8a2d\u6709\u5169\u500b\u8868\uff1ausers<\/code> \u548c orders<\/code>\uff0c\u6211\u5011\u53ef\u4ee5\u901a\u904e\u7528\u6236\u7684 ID \u5c07\u9019\u5169\u500b\u8868\u9023\u63a5\u8d77\u4f86\uff0c\u4ee5\u7372\u53d6\u7528\u6236\u7684\u8a02\u55ae\u4fe1\u606f\u3002<\/p>\n

SELECT users.name, orders.amount \nFROM users \nJOIN orders ON users.id = orders.user_id;<\/code><\/pre>\n
\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u7684\u6280\u5de7<\/h2>\n
1. \u4f7f\u7528\u7d22\u5f15<\/h3>\n
\u7d22\u5f15\u662f\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u7684\u95dc\u9375\u3002\u901a\u904e\u5728\u9023\u63a5\u7684\u6b04\u4f4d\u4e0a\u5275\u5efa\u7d22\u5f15\uff0c\u53ef\u4ee5\u986f\u8457\u6e1b\u5c11\u67e5\u8a62\u6240\u9700\u7684\u6642\u9593\u3002\u5c0d\u65bc\u4e0a\u8ff0\u7684\u4f8b\u5b50\uff0c\u5c0d users.id<\/code> \u548c orders.user_id<\/code> \u5275\u5efa\u7d22\u5f15\uff0c\u53ef\u4ee5\u52a0\u5feb\u67e5\u8a62\u901f\u5ea6\u3002<\/p>\n
CREATE INDEX idx_user_id ON users(id);\nCREATE INDEX idx_order_user_id ON orders(user_id);<\/code><\/pre>\n
2. \u907f\u514d\u4f7f\u7528 SELECT *<\/h3>\n
\u5728\u67e5\u8a62\u6642\uff0c\u907f\u514d\u4f7f\u7528 SELECT *<\/code>\uff0c\u56e0\u70ba\u9019\u6703\u5c0e\u81f4\u6578\u64da\u5eab\u8fd4\u56de\u6240\u6709\u6b04\u4f4d\uff0c\u589e\u52a0\u4e86\u4e0d\u5fc5\u8981\u7684\u8ca0\u64d4\u3002\u61c9\u8a72\u660e\u78ba\u6307\u5b9a\u9700\u8981\u7684\u6b04\u4f4d\uff0c\u4ee5\u6e1b\u5c11\u6578\u64da\u50b3\u8f38\u91cf\u3002<\/p>\n
SELECT users.name, orders.amount \nFROM users \nJOIN orders ON users.id = orders.user_id;<\/code><\/pre>\n
3. \u4f7f\u7528\u9069\u7576\u7684\u9023\u63a5\u985e\u578b<\/h3>\n
\u6839\u64da\u9700\u6c42\u9078\u64c7\u5408\u9069\u7684\u9023\u63a5\u985e\u578b\uff08\u5982 INNER JOIN\u3001LEFT JOIN\u3001RIGHT JOIN \u7b49\uff09\u4e5f\u80fd\u5f71\u97ff\u67e5\u8a62\u6548\u7387\u3002INNER JOIN \u901a\u5e38\u6bd4 LEFT JOIN \u66f4\u5feb\uff0c\u56e0\u70ba\u5b83\u53ea\u8fd4\u56de\u5339\u914d\u7684\u8a18\u9304\u3002<\/p>\n
4. \u512a\u5316\u67e5\u8a62\u689d\u4ef6<\/h3>\n
\u5728 WHERE \u5b50\u53e5\u4e2d\u4f7f\u7528\u9069\u7576\u7684\u689d\u4ef6\u53ef\u4ee5\u9032\u4e00\u6b65\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002\u78ba\u4fdd\u4f7f\u7528\u7684\u689d\u4ef6\u80fd\u5920\u5229\u7528\u7d22\u5f15\uff0c\u4e26\u907f\u514d\u4f7f\u7528\u4e0d\u5fc5\u8981\u7684\u8a08\u7b97\u6216\u51fd\u6578\u3002<\/p>\n
SELECT users.name, orders.amount \nFROM users \nJOIN orders ON users.id = orders.user_id \nWHERE orders.amount > 100;<\/code><\/pre>\n
5. \u5b9a\u671f\u7dad\u8b77\u6578\u64da\u5eab<\/h3>\n
\u5b9a\u671f\u9032\u884c\u6578\u64da\u5eab\u7dad\u8b77\uff0c\u5982\u91cd\u5efa\u7d22\u5f15\u548c\u66f4\u65b0\u7d71\u8a08\u4fe1\u606f\uff0c\u53ef\u4ee5\u4fdd\u6301\u6578\u64da\u5eab\u7684\u6027\u80fd\u3002\u9019\u4e9b\u64cd\u4f5c\u6709\u52a9\u65bc\u6578\u64da\u5eab\u512a\u5316\u67e5\u8a62\u8a08\u5283\uff0c\u5f9e\u800c\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/p>\n
\u7d50\u8ad6<\/h2>\n
\u5728\u9032\u884c SQL \u6709\u5e8f\u865f\u8868\u9023\u63a5\u6642\uff0c\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u662f\u78ba\u4fdd\u61c9\u7528\u7a0b\u5e8f\u6027\u80fd\u7684\u95dc\u9375\u3002\u901a\u904e\u4f7f\u7528\u7d22\u5f15\u3001\u907f\u514d\u4f7f\u7528 SELECT *<\/code>\u3001\u9078\u64c7\u9069\u7576\u7684\u9023\u63a5\u985e\u578b\u3001\u512a\u5316\u67e5\u8a62\u689d\u4ef6\u4ee5\u53ca\u5b9a\u671f\u7dad\u8b77\u6578\u64da\u5eab\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u986f\u8457\u63d0\u5347\u67e5\u8a62\u6027\u80fd\u3002\u9019\u4e9b\u6280\u5de7\u4e0d\u50c5\u9069\u7528\u65bc\u6709\u5e8f\u865f\u8868\u9023\u63a5\uff0c\u4e5f\u53ef\u4ee5\u61c9\u7528\u65bc\u5176\u4ed6\u985e\u578b\u7684 SQL \u67e5\u8a62\u4e2d\u3002<\/p>\n
\u5982\u9700\u4e86\u89e3\u66f4\u591a\u95dc\u65bc\u6578\u64da\u5eab\u6027\u80fd\u512a\u5316\u7684\u8cc7\u8a0a\uff0c\u60a8\u53ef\u4ee5\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9 Server.HK<\/a>\uff0c\u6211\u5011\u63d0\u4f9b\u5404\u7a2e VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0c\u5e6b\u52a9\u60a8\u63d0\u5347\u61c9\u7528\u7a0b\u5e8f\u7684\u6027\u80fd\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u63a2\u7d22\u5982\u4f55\u901a\u904e\u6709\u5e8f\u865f\u8868\u9023\u63a5\u512a\u5316 SQL \u67e5\u8a62\u6548\u7387\uff0c\u63d0\u5347\u6578\u64da\u5eab\u6027\u80fd\uff0c\u5be6\u73fe\u66f4\u5feb\u7684\u6578\u64da\u6aa2\u7d22\u548c\u8655\u7406\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-168429","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168429","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=168429"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168429\/revisions"}],"predecessor-version":[{"id":168430,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168429\/revisions\/168430"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=168429"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=168429"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=168429"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}