{"id":143769,"date":"2024-11-01T01:05:25","date_gmt":"2024-10-31T17:05:25","guid":{"rendered":"https:\/\/server.hk\/cnblog\/143769\/"},"modified":"2024-11-01T01:05:26","modified_gmt":"2024-10-31T17:05:26","slug":"sql-%e6%9f%a5%e8%a9%a2%e6%9c%80%e5%a4%a7%e6%9c%80%e5%b0%8f%e5%80%bc%e7%9a%84%e7%a4%ba%e4%be%8b","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/143769\/","title":{"rendered":"SQL \u67e5\u8a62\u6700\u5927\u6700\u5c0f\u503c\u7684\u793a\u4f8b"},"content":{"rendered":"

SQL \u67e5\u8a62\u6700\u5927\u6700\u5c0f\u503c\u7684\u793a\u4f8b<\/h1>\n

\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0cSQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u662f\u4e00\u7a2e\u7528\u65bc\u67e5\u8a62\u548c\u64cd\u4f5c\u6578\u64da\u7684\u5f37\u5927\u5de5\u5177\u3002\u67e5\u8a62\u6578\u64da\u7684\u6700\u5927\u503c\u548c\u6700\u5c0f\u503c\u662f\u6578\u64da\u5206\u6790\u4e2d\u5e38\u898b\u7684\u9700\u6c42\uff0c\u5c24\u5176\u662f\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u5982\u4f55\u4f7f\u7528 SQL \u67e5\u8a62\u4f86\u7372\u53d6\u6578\u64da\u8868\u4e2d\u7684\u6700\u5927\u503c\u548c\u6700\u5c0f\u503c\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5be6\u7528\u7684\u793a\u4f8b\u3002<\/p>\n

\u57fa\u672c\u6982\u5ff5<\/h2>\n

\u5728 SQL \u4e2d\uff0c\u7372\u53d6\u6700\u5927\u503c\u548c\u6700\u5c0f\u503c\u901a\u5e38\u4f7f\u7528 MAX()<\/code> \u548c MIN()<\/code> \u51fd\u6578\u3002\u9019\u4e9b\u51fd\u6578\u53ef\u4ee5\u7528\u65bc\u4efb\u4f55\u6578\u503c\u578b\u6216\u65e5\u671f\u578b\u7684\u5217\uff0c\u4e26\u8fd4\u56de\u8a72\u5217\u4e2d\u7684\u6700\u5927\u6216\u6700\u5c0f\u503c\u3002<\/p>\n

\u4f7f\u7528 MAX() \u548c MIN() \u51fd\u6578<\/h2>\n

\u4ee5\u4e0b\u662f\u4f7f\u7528 MAX()<\/code> \u548c MIN()<\/code> \u51fd\u6578\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n

SELECT MAX(column_name) FROM table_name;\nSELECT MIN(column_name) FROM table_name;<\/code><\/pre>\n
\u5728\u9019\u88e1\uff0ccolumn_name<\/code> \u662f\u4f60\u60f3\u8981\u67e5\u8a62\u7684\u5217\u540d\uff0c\u800c table_name<\/code> \u662f\u6578\u64da\u8868\u7684\u540d\u7a31\u3002<\/p>\n
\u793a\u4f8b\uff1a\u67e5\u8a62\u5b78\u751f\u7684\u6700\u9ad8\u548c\u6700\u4f4e\u5206\u6578<\/h3>\n
\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba students<\/code> \u7684\u6578\u64da\u8868\uff0c\u8a72\u8868\u5305\u542b\u5b78\u751f\u7684\u59d3\u540d\u548c\u5206\u6578\u3002\u8868\u7d50\u69cb\u5982\u4e0b\uff1a<\/p>\n
CREATE TABLE students (\n    id INT PRIMARY KEY,\n    name VARCHAR(100),\n    score INT\n);<\/code><\/pre>\n
\u6211\u5011\u53ef\u4ee5\u63d2\u5165\u4e00\u4e9b\u793a\u4f8b\u6578\u64da\uff1a<\/p>\n
INSERT INTO students (id, name, score) VALUES\n(1, 'Alice', 85),\n(2, 'Bob', 92),\n(3, 'Charlie', 78),\n(4, 'David', 88);<\/code><\/pre>\n
\u73fe\u5728\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8a62\u4f86\u7372\u53d6\u6700\u9ad8\u548c\u6700\u4f4e\u5206\u6578\uff1a<\/p>\n
SELECT MAX(score) AS highest_score FROM students;\nSELECT MIN(score) AS lowest_score FROM students;<\/code><\/pre>\n
\u57f7\u884c\u9019\u4e9b\u67e5\u8a62\u5f8c\uff0c\u5c07\u8fd4\u56de\u6700\u9ad8\u5206\u6578 92 \u548c\u6700\u4f4e\u5206\u6578 78\u3002<\/p>\n
\u67e5\u8a62\u7279\u5b9a\u689d\u4ef6\u4e0b\u7684\u6700\u5927\u6700\u5c0f\u503c<\/h3>\n
\u6709\u6642\uff0c\u6211\u5011\u53ef\u80fd\u9700\u8981\u6839\u64da\u7279\u5b9a\u689d\u4ef6\u4f86\u67e5\u8a62\u6700\u5927\u503c\u548c\u6700\u5c0f\u503c\u3002\u4f8b\u5982\uff0c\u5982\u679c\u6211\u5011\u53ea\u60f3\u67e5\u8a62\u5206\u6578\u5927\u65bc 80 \u7684\u5b78\u751f\u7684\u6700\u9ad8\u5206\u6578\uff0c\u53ef\u4ee5\u4f7f\u7528 WHERE<\/code> \u5b50\u53e5\uff1a<\/p>\n
SELECT MAX(score) AS highest_score FROM students WHERE score > 80;<\/code><\/pre>\n
\u9019\u5c07\u8fd4\u56de 92\uff0c\u56e0\u70ba\u53ea\u6709 Alice\u3001Bob \u548c David \u7684\u5206\u6578\u7b26\u5408\u689d\u4ef6\u3002<\/p>\n
\u7d50\u5408 GROUP BY \u4f7f\u7528<\/h2>\n
\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u6211\u5011\u53ef\u80fd\u9700\u8981\u6309\u67d0\u500b\u5217\u5206\u7d44\u4e26\u67e5\u8a62\u6bcf\u7d44\u7684\u6700\u5927\u503c\u548c\u6700\u5c0f\u503c\u3002\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u5728 students<\/code> \u8868\u4e2d\u6dfb\u52a0\u4e00\u500b\u73ed\u7d1a\u5217\uff1a<\/p>\n
ALTER TABLE students ADD class VARCHAR(10);<\/code><\/pre>\n
\u7136\u5f8c\u63d2\u5165\u4e00\u4e9b\u6578\u64da\uff1a<\/p>\n
UPDATE students SET class = 'A' WHERE id IN (1, 2);\nUPDATE students SET class = 'B' WHERE id IN (3, 4);<\/code><\/pre>\n
\u73fe\u5728\uff0c\u6211\u5011\u53ef\u4ee5\u67e5\u8a62\u6bcf\u500b\u73ed\u7d1a\u7684\u6700\u9ad8\u548c\u6700\u4f4e\u5206\u6578\uff1a<\/p>\n
SELECT class, MAX(score) AS highest_score, MIN(score) AS lowest_score\nFROM students\nGROUP BY class;<\/code><\/pre>\n
\u9019\u5c07\u8fd4\u56de\u6bcf\u500b\u73ed\u7d1a\u7684\u6700\u9ad8\u548c\u6700\u4f4e\u5206\u6578\uff0c\u5e6b\u52a9\u6211\u5011\u66f4\u597d\u5730\u4e86\u89e3\u4e0d\u540c\u73ed\u7d1a\u7684\u8868\u73fe\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
\u4f7f\u7528 SQL \u67e5\u8a62\u6700\u5927\u503c\u548c\u6700\u5c0f\u503c\u662f\u6578\u64da\u5206\u6790\u4e2d\u7684\u57fa\u672c\u6280\u80fd\u3002\u901a\u904e MAX()<\/code> \u548c MIN()<\/code> \u51fd\u6578\uff0c\u6211\u5011\u53ef\u4ee5\u8f15\u9b06\u7372\u53d6\u6240\u9700\u7684\u6578\u64da\uff0c\u4e26\u6839\u64da\u9700\u8981\u9032\u884c\u9032\u4e00\u6b65\u7684\u5206\u6790\u3002\u7121\u8ad6\u662f\u55ae\u7d14\u7684\u67e5\u8a62\u9084\u662f\u7d50\u5408\u689d\u4ef6\u548c\u5206\u7d44\uff0c\u9019\u4e9b\u529f\u80fd\u90fd\u80fd\u5e6b\u52a9\u6211\u5011\u66f4\u6709\u6548\u5730\u7ba1\u7406\u548c\u5206\u6790\u6578\u64da\u3002<\/p>\n
\u5982\u679c\u60a8\u9700\u8981\u7a69\u5b9a\u7684 \u9999\u6e2fVPS<\/a> \u4f86\u904b\u884c\u60a8\u7684\u6578\u64da\u5eab\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u9700\u6c42\u3002\u7121\u8ad6\u662f\u5c0f\u578b\u9805\u76ee\u9084\u662f\u5927\u578b\u61c9\u7528\uff0c\u6211\u5011\u7684 \u4f3a\u670d\u5668<\/a> \u89e3\u6c7a\u65b9\u6848\u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e86\u89e3\u5982\u4f55\u4f7f\u7528 SQL \u67e5\u8a62\u4f86\u7372\u53d6\u6578\u64da\u96c6\u4e2d\u7684\u6700\u5927\u503c\u548c\u6700\u5c0f\u503c\uff0c\u4e26\u67e5\u770b\u793a\u4f8b\u4ee5\u8f15\u9b06\u61c9\u7528\u65bc\u60a8\u7684\u6578\u64da\u5eab\u67e5\u8a62\u4e2d\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-143769","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/143769","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=143769"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/143769\/revisions"}],"predecessor-version":[{"id":143770,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/143769\/revisions\/143770"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=143769"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=143769"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=143769"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}