{"id":168521,"date":"2024-11-06T13:04:30","date_gmt":"2024-11-06T05:04:30","guid":{"rendered":"https:\/\/server.hk\/cnblog\/168521\/"},"modified":"2024-11-06T13:04:31","modified_gmt":"2024-11-06T05:04:31","slug":"sql-%e4%b8%ad%e5%b8%b8%e8%a2%ab%e5%bf%bd%e8%a6%96%e7%9a%84%e5%85%ab%e7%a8%ae%e9%8c%af%e8%aa%a4%e7%94%a8%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/168521\/","title":{"rendered":"SQL \u4e2d\u5e38\u88ab\u5ffd\u8996\u7684\u516b\u7a2e\u932f\u8aa4\u7528\u6cd5"},"content":{"rendered":"

SQL \u4e2d\u5e38\u88ab\u5ffd\u8996\u7684\u516b\u7a2e\u932f\u8aa4\u7528\u6cd5<\/h1>\n

\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0cSQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u662f\u6700\u5e38\u7528\u7684\u8a9e\u8a00\u4e4b\u4e00\u3002\u96d6\u7136 SQL \u7684\u8a9e\u6cd5\u76f8\u5c0d\u7c21\u55ae\uff0c\u4f46\u8a31\u591a\u958b\u767c\u8005\u5728\u4f7f\u7528\u904e\u7a0b\u4e2d\u5e38\u5e38\u6703\u72af\u4e00\u4e9b\u932f\u8aa4\uff0c\u9019\u4e9b\u932f\u8aa4\u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u4e0b\u964d\u6216\u6578\u64da\u4e0d\u4e00\u81f4\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u516b\u7a2e\u5e38\u88ab\u5ffd\u8996\u7684 SQL \u932f\u8aa4\u7528\u6cd5\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u63d0\u9ad8 SQL \u67e5\u8a62\u7684\u6548\u7387\u548c\u6e96\u78ba\u6027\u3002<\/p>\n

1. \u5ffd\u7565\u7d22\u5f15\u7684\u4f7f\u7528<\/h2>\n

\u7d22\u5f15\u662f\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u7684\u91cd\u8981\u5de5\u5177\u3002\u8a31\u591a\u958b\u767c\u8005\u5728\u8a2d\u8a08\u6578\u64da\u5eab\u6642\uff0c\u5f80\u5f80\u5ffd\u7565\u4e86\u70ba\u8868\u683c\u6dfb\u52a0\u7d22\u5f15\u3002\u9019\u6703\u5c0e\u81f4\u67e5\u8a62\u901f\u5ea6\u7de9\u6162\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\u3002<\/p>\n

-- \u5efa\u7acb\u7d22\u5f15\u7684\u7bc4\u4f8b\nCREATE INDEX idx_user_name ON users(name);\n<\/code><\/pre>\n
2. \u4f7f\u7528 SELECT *<\/h2>\n
\u4f7f\u7528 SELECT *<\/code> \u6703\u9078\u64c7\u8868\u4e2d\u7684\u6240\u6709\u5217\uff0c\u9019\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\u53ef\u80fd\u6703\u5c0e\u81f4\u4e0d\u5fc5\u8981\u7684\u6578\u64da\u50b3\u8f38\u548c\u6027\u80fd\u554f\u984c\u3002\u5efa\u8b70\u660e\u78ba\u6307\u5b9a\u6240\u9700\u7684\u5217\u3002<\/p>\n
-- \u5118\u91cf\u907f\u514d\u4f7f\u7528 SELECT *\nSELECT name, email FROM users;\n<\/code><\/pre>\n
3. \u5ffd\u8996 NULL \u503c\u7684\u8655\u7406<\/h2>\n
\u5728 SQL \u4e2d\uff0cNULL \u503c\u7684\u8655\u7406\u5e38\u5e38\u88ab\u5ffd\u8996\u3002\u958b\u767c\u8005\u61c9\u8a72\u6e05\u695a NULL \u503c\u7684\u610f\u7fa9\uff0c\u4e26\u5728\u67e5\u8a62\u4e2d\u6b63\u78ba\u8655\u7406\u5b83\u5011\uff0c\u4ee5\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u932f\u8aa4\u3002<\/p>\n
-- \u6b63\u78ba\u8655\u7406 NULL \u503c\u7684\u7bc4\u4f8b\nSELECT * FROM users WHERE email IS NOT NULL;\n<\/code><\/pre>\n
4. \u4e0d\u4f7f\u7528\u4e8b\u52d9<\/h2>\n
\u5728\u9032\u884c\u591a\u500b SQL \u64cd\u4f5c\u6642\uff0c\u672a\u4f7f\u7528\u4e8b\u52d9\u53ef\u80fd\u6703\u5c0e\u81f4\u6578\u64da\u4e0d\u4e00\u81f4\u3002\u4e8b\u52d9\u53ef\u4ee5\u78ba\u4fdd\u4e00\u7d44\u64cd\u4f5c\u8981\u9ebc\u5168\u90e8\u6210\u529f\uff0c\u8981\u9ebc\u5168\u90e8\u5931\u6557\u3002<\/p>\n
-- \u4f7f\u7528\u4e8b\u52d9\u7684\u7bc4\u4f8b\nBEGIN;\nUPDATE accounts SET balance = balance - 100 WHERE user_id = 1;\nUPDATE accounts SET balance = balance + 100 WHERE user_id = 2;\nCOMMIT;\n<\/code><\/pre>\n
5. \u5ffd\u7565 SQL \u6ce8\u5165\u7684\u98a8\u96aa<\/h2>\n
SQL \u6ce8\u5165\u662f\u4e00\u7a2e\u5e38\u898b\u7684\u5b89\u5168\u6f0f\u6d1e\uff0c\u958b\u767c\u8005\u61c9\u8a72\u4f7f\u7528\u53c3\u6578\u5316\u67e5\u8a62\u4f86\u9632\u6b62\u9019\u7a2e\u653b\u64ca\u3002<\/p>\n
-- \u4f7f\u7528\u53c3\u6578\u5316\u67e5\u8a62\u7684\u7bc4\u4f8b\nSELECT * FROM users WHERE username = ? AND password = ?;\n<\/code><\/pre>\n
6. \u4e0d\u5408\u7406\u7684 JOIN \u4f7f\u7528<\/h2>\n
\u5728\u9032\u884c\u591a\u8868\u67e5\u8a62\u6642\uff0c\u4f7f\u7528\u4e0d\u5408\u7406\u7684 JOIN \u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u554f\u984c\u3002\u958b\u767c\u8005\u61c9\u8a72\u6839\u64da\u9700\u6c42\u9078\u64c7\u5408\u9069\u7684 JOIN \u985e\u578b\u3002<\/p>\n
-- \u4f7f\u7528 INNER JOIN \u7684\u7bc4\u4f8b\nSELECT users.name, orders.amount \nFROM users \nINNER JOIN orders ON users.id = orders.user_id;\n<\/code><\/pre>\n
7. \u5ffd\u8996\u67e5\u8a62\u8a08\u5283<\/h2>\n
\u67e5\u8a62\u8a08\u5283\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u4e86\u89e3 SQL \u67e5\u8a62\u7684\u57f7\u884c\u65b9\u5f0f\u3002\u5ffd\u8996\u67e5\u8a62\u8a08\u5283\u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u554f\u984c\uff0c\u5efa\u8b70\u5b9a\u671f\u6aa2\u67e5\u548c\u512a\u5316\u67e5\u8a62\u8a08\u5283\u3002<\/p>\n
-- \u67e5\u770b\u67e5\u8a62\u8a08\u5283\u7684\u7bc4\u4f8b\nEXPLAIN SELECT * FROM users WHERE age > 30;\n<\/code><\/pre>\n
8. \u4e0d\u5b9a\u671f\u6e05\u7406\u6578\u64da<\/h2>\n
\u96a8\u8457\u6642\u9593\u7684\u63a8\u79fb\uff0c\u6578\u64da\u5eab\u4e2d\u7684\u6578\u64da\u6703\u4e0d\u65b7\u589e\u9577\uff0c\u672a\u5b9a\u671f\u6e05\u7406\u904e\u671f\u6216\u4e0d\u5fc5\u8981\u7684\u6578\u64da\u6703\u5f71\u97ff\u6027\u80fd\u3002\u5b9a\u671f\u9032\u884c\u6578\u64da\u6e05\u7406\u662f\u4fdd\u6301\u6578\u64da\u5eab\u5065\u5eb7\u7684\u91cd\u8981\u6b65\u9a5f\u3002<\/p>\n
-- \u522a\u9664\u904e\u671f\u6578\u64da\u7684\u7bc4\u4f8b\nDELETE FROM sessions WHERE last_access < NOW() - INTERVAL 30 DAY;\n<\/code><\/pre>\n
\u7e3d\u7d50<\/h2>\n
\u5728\u4f7f\u7528 SQL \u6642\uff0c\u958b\u767c\u8005\u61c9\u8a72\u6ce8\u610f\u4ee5\u4e0a\u516b\u7a2e\u5e38\u88ab\u5ffd\u8996\u7684\u932f\u8aa4\u7528\u6cd5\uff0c\u4ee5\u63d0\u9ad8\u67e5\u8a62\u7684\u6548\u7387\u548c\u5b89\u5168\u6027\u3002\u900f\u904e\u6b63\u78ba\u7684\u7d22\u5f15\u4f7f\u7528\u3001\u5408\u7406\u7684\u67e5\u8a62\u8a2d\u8a08\u4ee5\u53ca\u5b9a\u671f\u7684\u6578\u64da\u6e05\u7406\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u63d0\u5347\u6578\u64da\u5eab\u7684\u6027\u80fd\u3002\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 \u9999\u6e2f VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u63a2\u7d22 SQL \u4e2d\u5e38\u88ab\u5ffd\u8996\u7684\u516b\u7a2e\u932f\u8aa4\u7528\u6cd5\uff0c\u907f\u514d\u5e38\u898b\u9677\u9631\uff0c\u63d0\u5347\u6578\u64da\u5eab\u67e5\u8a62\u6548\u7387\u8207\u6e96\u78ba\u6027\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-168521","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168521","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=168521"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168521\/revisions"}],"predecessor-version":[{"id":168522,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168521\/revisions\/168522"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=168521"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=168521"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=168521"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}