{"id":199693,"date":"2025-05-06T10:13:48","date_gmt":"2025-05-06T02:13:48","guid":{"rendered":"https:\/\/server.hk\/cnblog\/199693\/"},"modified":"2025-05-06T10:13:48","modified_gmt":"2025-05-06T02:13:48","slug":"%e4%bd%bf%e7%94%a8group-by%e5%af%b9%e6%95%b0%e6%8d%ae%e8%bf%9b%e8%a1%8c%e5%88%86%e7%bb%84","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/199693\/","title":{"rendered":"\u4f7f\u7528GROUP BY\u5bf9\u6570\u636e\u8fdb\u884c\u5206\u7ec4"},"content":{"rendered":"

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

\u4f7f\u7528GROUP BY\u5bf9\u6570\u636e\u8fdb\u884c\u5206\u7ec4<\/h1>\n

\u6765\u5230\u4e3b\u673a\u5b9d\u8d1d\u7684\u5927\u5bb6\uff0c\u76f8\u4fe1\u90fd\u662f\u7f16\u7a0b\u5b66\u4e60\u7231\u597d\u8005\uff0c\u5e0c\u671b\u5728\u8fd9\u91cc\u5b66\u4e60\u6570\u636e\u5e93\u76f8\u5173\u7f16\u7a0b\u77e5\u8bc6\u3002\u4e0b\u9762\u672c\u7bc7\u6587\u7ae0\u5c31\u6765\u5e26\u5927\u5bb6\u804a\u804a\u300a\u4f7f\u7528GROUP BY\u5bf9\u6570\u636e\u8fdb\u884c\u5206\u7ec4\u300b\uff0c\u4ecb\u7ecd\u4e00\u4e0b\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u7684\u77e5\u8bc6\u79ef\u7d2f\u6709\u6240\u5e2e\u52a9\uff0c\u52a9\u529b\u5b9e\u6218\u5f00\u53d1\uff01<\/p>\n

Group by\u662f\u4e00\u79cd\u5728\u6570\u636e\u5e93\u67e5\u8be2\u4e2d\u975e\u5e38\u5e38\u7528\u7684\u8bed\u53e5\uff0c\u5b83\u7528\u4e8e\u6309\u7167\u67d0\u4e2a\u5b57\u6bb5\u5bf9\u6570\u636e\u8fdb\u884c\u5206\u7ec4\uff0c\u5e76\u5bf9\u6bcf\u4e2a\u5206\u7ec4\u8fdb\u884c\u805a\u5408\u8ba1\u7b97\u3002\u5728\u5b9e\u9645\u5e94\u7528\u4e2d\uff0cGroup by\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u5feb\u901f\u5206\u6790\u6570\u636e\u5e76\u63d0\u53d6\u6709\u610f\u4e49\u7684\u7edf\u8ba1\u4fe1\u606f\u3002<\/p>\n

Group by\u8bed\u53e5\u7684\u57fa\u672c\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n

SELECT \u5217\u540d, \u805a\u5408\u51fd\u6570(\u5217\u540d)\nFROM \u8868\u540d\nGROUP BY \u5217\u540d<\/pre>\n
\u5176\u4e2d\uff0c\u5217\u540d\u662f\u6211\u4eec\u60f3\u8981\u6309\u7167\u5176\u8fdb\u884c\u5206\u7ec4\u7684\u5b57\u6bb5\u3002\u805a\u5408\u51fd\u6570\u662f\u5bf9\u5206\u7ec4\u540e\u7684\u6570\u636e\u8fdb\u884c\u8ba1\u7b97\u7684\u51fd\u6570\uff0c\u6bd4\u5982\u6c42\u548c\u3001\u5e73\u5747\u503c\u3001\u6700\u5927\u503c\u7b49\u3002\u8868\u540d\u5219\u662f\u6570\u636e\u6240\u5728\u7684\u6570\u636e\u5e93\u8868\u3002<\/p>\n
\u4e0b\u9762\u6211\u4eec\u4ee5\u4e00\u4e2a\u793a\u4f8b\u6765\u8fdb\u4e00\u6b65\u8bf4\u660eGroup by\u7684\u7528\u6cd5\u3002\u5047\u8bbe\u6211\u4eec\u6709\u4e00\u4e2a\u5b66\u751f\u6210\u7ee9\u8868\uff0c\u5305\u542b\u4e86\u5b66\u751f\u7684\u59d3\u540d\u548c\u6210\u7ee9\uff0c\u6211\u4eec\u5e0c\u671b\u6309\u7167\u5b66\u751f\u7684\u59d3\u540d\u5206\u7ec4\uff0c\u5e76\u8ba1\u7b97\u6bcf\u4e2a\u5b66\u751f\u7684\u5e73\u5747\u6210\u7ee9\u3002<\/p>\n
\u9996\u5148\uff0c\u6211\u4eec\u521b\u5efa\u4e00\u4e2a\u540d\u4e3a\u201cstudent_scores\u201d\u7684\u8868\uff0c\u8be5\u8868\u5305\u542b\u4e24\u5217\uff1a\u59d3\u540d\uff08name\uff09\u548c\u6210\u7ee9\uff08score\uff09\u3002<\/p>\n
CREATE TABLE student_scores (\n    name VARCHAR(50),\n    score INT\n);\n\nINSERT INTO student_scores (name, score)\nVALUES ('\u5f20\u4e09', 90),\n       ('\u674e\u56db', 80),\n       ('\u5f20\u4e09', 95),\n       ('\u738b\u4e94', 85),\n       ('\u674e\u56db', 75);<\/pre>\n
\u63a5\u4e0b\u6765\uff0c\u6211\u4eec\u4f7f\u7528Group by\u8bed\u53e5\u67e5\u8be2\u6bcf\u4e2a\u5b66\u751f\u7684\u5e73\u5747\u6210\u7ee9\u3002<\/p>\n
SELECT name, AVG(score) AS avg_score\nFROM student_scores\nGROUP BY name;<\/pre>\n
\u4ee5\u4e0a\u4ee3\u7801\u4e2d\uff0cname\u5217\u662f\u6211\u4eec\u60f3\u8981\u6309\u7167\u5176\u8fdb\u884c\u5206\u7ec4\u7684\u5b57\u6bb5\uff1bAVG(score)\u662f\u5bf9\u6bcf\u4e2a\u5206\u7ec4\u7684\u6210\u7ee9\u8fdb\u884c\u5e73\u5747\u503c\u8ba1\u7b97\u7684\u805a\u5408\u51fd\u6570\uff1bAS avg_score\u7528\u4e8e\u7ed9\u8ba1\u7b97\u7ed3\u679c\u8d77\u4e00\u4e2a\u522b\u540d\u3002<\/p>\n
\u6267\u884c\u4ee5\u4e0a\u67e5\u8be2\u8bed\u53e5\u540e\uff0c\u6211\u4eec\u5c06\u5f97\u5230\u4ee5\u4e0b\u7ed3\u679c\uff1a<\/p>\n
name | avg_score\n--------------\n\u5f20\u4e09    | 92.5\n\u674e\u56db    | 77.5\n\u738b\u4e94    | 85.0<\/pre>\n
\u53ef\u4ee5\u770b\u5230\uff0c\u67e5\u8be2\u7ed3\u679c\u6309\u7167\u5b66\u751f\u7684\u59d3\u540d\u8fdb\u884c\u4e86\u5206\u7ec4\uff0c\u5e76\u8ba1\u7b97\u51fa\u4e86\u6bcf\u4e2a\u5b66\u751f\u7684\u5e73\u5747\u6210\u7ee9\u3002<\/p>\n
\u9664\u4e86\u7b80\u5355\u7684\u6c42\u5e73\u5747\u503c\u4e4b\u5916\uff0cGroup by\u8bed\u53e5\u8fd8\u53ef\u4ee5\u7ed3\u5408\u5176\u4ed6\u805a\u5408\u51fd\u6570\u8fdb\u884c\u66f4\u52a0\u590d\u6742\u7684\u7edf\u8ba1\u8ba1\u7b97\u3002\u4e0b\u9762\u662f\u4e00\u4e9b\u5e38\u7528\u7684\u805a\u5408\u51fd\u6570\uff1a<\/p>\n
    \n
  • SUM\uff1a\u6c42\u548c<\/li>\n
  • COUNT\uff1a\u8ba1\u6570<\/li>\n
  • MAX\uff1a\u6700\u5927\u503c<\/li>\n
  • MIN\uff1a\u6700\u5c0f\u503c<\/li>\n<\/ul>\n
    \u4f8b\u5982\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528COUNT\u51fd\u6570\u6765\u7edf\u8ba1\u6bcf\u4e2a\u5b66\u751f\u7684\u8003\u8bd5\u6b21\u6570\uff1a<\/p>\n
    SELECT name, COUNT(score) AS exam_times\nFROM student_scores\nGROUP BY name;<\/pre>\n
    \u6267\u884c\u4ee5\u4e0a\u67e5\u8be2\u8bed\u53e5\u540e\uff0c\u6211\u4eec\u5c06\u5f97\u5230\u4ee5\u4e0b\u7ed3\u679c\uff1a<\/p>\n
    name | exam_times\n--------------\n\u5f20\u4e09   |      2\n\u674e\u56db   |      2\n\u738b\u4e94   |      1<\/pre>\n
    \u53ef\u4ee5\u770b\u5230\uff0c\u67e5\u8be2\u7ed3\u679c\u6309\u7167\u5b66\u751f\u7684\u59d3\u540d\u8fdb\u884c\u4e86\u5206\u7ec4\uff0c\u5e76\u7edf\u8ba1\u51fa\u4e86\u6bcf\u4e2a\u5b66\u751f\u7684\u8003\u8bd5\u6b21\u6570\u3002<\/p>\n
    \u7efc\u4e0a\u6240\u8ff0\uff0cGroup by\u662f\u5728\u6570\u636e\u5e93\u67e5\u8be2\u4e2d\u975e\u5e38\u6709\u7528\u7684\u8bed\u53e5\u3002\u901a\u8fc7\u7ed3\u5408\u805a\u5408\u51fd\u6570\uff0c\u6211\u4eec\u53ef\u4ee5\u65b9\u4fbf\u5730\u5bf9\u6570\u636e\u8fdb\u884c\u5206\u7ec4\u548c\u7edf\u8ba1\u5206\u6790\u3002\u4e0d\u8bba\u662f\u6c42\u5e73\u5747\u503c\u3001\u603b\u548c\u3001\u6700\u5927\u503c\u8fd8\u662f\u6700\u5c0f\u503c\uff0cGroup by\u8bed\u53e5\u90fd\u80fd\u5e2e\u52a9\u6211\u4eec\u8f7b\u677e\u83b7\u53d6\u5230\u9700\u8981\u7684\u7edf\u8ba1\u4fe1\u606f\u3002<\/p>\n
    \u7406\u8bba\u8981\u638c\u63e1\uff0c\u5b9e\u64cd\u4e0d\u80fd\u843d\uff01\u4ee5\u4e0a\u5173\u4e8e\u300a\u4f7f\u7528GROUP BY\u5bf9\u6570\u636e\u8fdb\u884c\u5206\u7ec4\u300b\u7684\u8be6\u7ec6\u4ecb\u7ecd\uff0c\u5927\u5bb6\u90fd\u638c\u63e1\u4e86\u5427\uff01\u5982\u679c\u60f3\u8981\u7ee7\u7eed\u63d0\u5347\u81ea\u5df1\u7684\u80fd\u529b\uff0c\u90a3\u4e48\u5c31\u6765\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u5427\uff01<\/p>\n
    \n
    \n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"
    \u4f7f\u7528GROUP BY\u5bf9\u6570\u636e\u8fdb\u884c\u5206...<\/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-199693","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/199693","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=199693"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/199693\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=199693"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=199693"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=199693"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}