\u5728\u4f7f\u7528MySQL\u6578\u64da\u5eab\u6642\uff0c\u958b\u767c\u8005\u53ef\u80fd\u6703\u9047\u5230\u5404\u7a2e\u932f\u8aa4\uff0c\u5176\u4e2d\u4e4b\u4e00\u5c31\u662f\u932f\u8aa41172\uff0c\u8a72\u932f\u8aa4\u7684\u4ee3\u78bc\u70baSQLSTATE: 42000\uff08ER_TOO_MANY_ROWS\uff09\u3002\u9019\u500b\u932f\u8aa4\u901a\u5e38\u767c\u751f\u5728\u57f7\u884c\u67e5\u8a62\u6642\uff0c\u7576\u67e5\u8a62\u7684\u7d50\u679c\u8fd4\u56de\u591a\u65bc\u4e00\u884c\u7684\u6578\u64da\uff0c\u800c\u7cfb\u7d71\u9810\u671f\u53ea\u8fd4\u56de\u4e00\u884c\u6642\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u9019\u500b\u932f\u8aa4\u7684\u539f\u56e0\u3001\u5f71\u97ff\u4ee5\u53ca\u5982\u4f55\u6709\u6548\u5730\u4fee\u5fa9\u5b83\u3002<\/p>\n
\u932f\u8aa41172\u7684\u4e3b\u8981\u539f\u56e0\u662f\u57f7\u884c\u7684SQL\u67e5\u8a62\u8a66\u5716\u5c07\u591a\u884c\u7d50\u679c\u8ce6\u503c\u7d66\u4e00\u500b\u8b8a\u91cf\u6216\u5728\u4e00\u500b\u4e0a\u4e0b\u6587\u4e2d\u4f7f\u7528\uff0c\u9019\u500b\u4e0a\u4e0b\u6587\u53ea\u5141\u8a31\u55ae\u884c\u7d50\u679c\u3002\u4f8b\u5982\uff0c\u7576\u4f7f\u7528SELECT\u8a9e\u53e5\u67e5\u8a62\u6578\u64da\u6642\uff0c\u5982\u679c\u67e5\u8a62\u7684\u689d\u4ef6\u4e0d\u5920\u56b4\u683c\uff0c\u53ef\u80fd\u6703\u8fd4\u56de\u591a\u884c\u6578\u64da\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u793a\u4f8b\uff1a<\/p>\n
SELECT name FROM users WHERE age > 20;<\/code><\/pre>\n\u5982\u679c\u9019\u500b\u67e5\u8a62\u8fd4\u56de\u4e86\u591a\u65bc\u4e00\u500b\u7528\u6236\u7684\u540d\u5b57\uff0c\u800c\u4f60\u537b\u8a66\u5716\u5c07\u5176\u8ce6\u503c\u7d66\u4e00\u500b\u8b8a\u91cf\uff0c\u5247\u6703\u5c0e\u81f4\u932f\u8aa41172\u7684\u767c\u751f\u3002<\/p>\n
\u5982\u4f55\u4fee\u5fa9\u932f\u8aa41172<\/h2>\n
\u4fee\u5fa9\u932f\u8aa41172\u7684\u95dc\u9375\u5728\u65bc\u78ba\u4fdd\u67e5\u8a62\u7684\u7d50\u679c\u53ea\u8fd4\u56de\u4e00\u884c\u6578\u64da\u3002\u4ee5\u4e0b\u662f\u5e7e\u7a2e\u5e38\u898b\u7684\u89e3\u6c7a\u65b9\u6848\uff1a<\/p>\n
1. \u4f7f\u7528LIMIT\u5b50\u53e5<\/h3>\n
\u5982\u679c\u4f60\u53ea\u9700\u8981\u67e5\u8a62\u7684\u7b2c\u4e00\u884c\u6578\u64da\uff0c\u53ef\u4ee5\u4f7f\u7528LIMIT\u5b50\u53e5\u4f86\u9650\u5236\u8fd4\u56de\u7684\u884c\u6578\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT name FROM users WHERE age > 20 LIMIT 1;<\/code><\/pre>\n\u9019\u6a23\uff0c\u7121\u8ad6\u67e5\u8a62\u7684\u7d50\u679c\u6709\u591a\u5c11\u884c\uff0c\u7cfb\u7d71\u53ea\u6703\u8fd4\u56de\u7b2c\u4e00\u884c\u6578\u64da\uff0c\u5f9e\u800c\u907f\u514d\u4e86\u932f\u8aa41172\u7684\u767c\u751f\u3002<\/p>\n
2. \u4f7f\u7528\u805a\u5408\u51fd\u6578<\/h3>\n
\u5982\u679c\u4f60\u9700\u8981\u5c0d\u591a\u884c\u6578\u64da\u9032\u884c\u8a08\u7b97\uff0c\u53ef\u4ee5\u4f7f\u7528\u805a\u5408\u51fd\u6578\uff0c\u5982COUNT\u3001SUM\u3001AVG\u7b49\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT COUNT(*) FROM users WHERE age > 20;<\/code><\/pre>\n\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u8fd4\u56de\u4e00\u500b\u6574\u6578\uff0c\u8868\u793a\u7b26\u5408\u689d\u4ef6\u7684\u7528\u6236\u6578\u91cf\uff0c\u800c\u4e0d\u6703\u8fd4\u56de\u591a\u884c\u6578\u64da\u3002<\/p>\n
3. \u6aa2\u67e5\u67e5\u8a62\u689d\u4ef6<\/h3>\n
\u78ba\u4fdd\u67e5\u8a62\u7684\u689d\u4ef6\u8db3\u5920\u56b4\u683c\uff0c\u4ee5\u4fbf\u53ea\u8fd4\u56de\u4e00\u884c\u6578\u64da\u3002\u4f60\u53ef\u4ee5\u901a\u904e\u6dfb\u52a0\u66f4\u591a\u7684\u904e\u6ffe\u689d\u4ef6\u4f86\u9054\u5230\u9019\u4e00\u9ede\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT name FROM users WHERE age = 25 AND city = 'Hong Kong';<\/code><\/pre>\n\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u66f4\u6709\u53ef\u80fd\u8fd4\u56de\u552f\u4e00\u7684\u4e00\u884c\u6578\u64da\uff0c\u5f9e\u800c\u907f\u514d\u932f\u8aa41172\u3002<\/p>\n
4. \u4f7f\u7528\u5b50\u67e5\u8a62<\/h3>\n
\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528\u5b50\u67e5\u8a62\u53ef\u4ee5\u5e6b\u52a9\u4f60\u7372\u5f97\u6240\u9700\u7684\u55ae\u884c\u7d50\u679c\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT name FROM (SELECT name FROM users WHERE age > 20) AS temp LIMIT 1;<\/code><\/pre>\n\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u9996\u5148\u5f9eusers\u8868\u4e2d\u9078\u64c7\u6240\u6709\u5e74\u9f61\u5927\u65bc20\u7684\u7528\u6236\uff0c\u7136\u5f8c\u5f9e\u4e2d\u9078\u64c7\u7b2c\u4e00\u884c\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
MySQL\u932f\u8aa41172\uff08SQLSTATE: 42000\uff09\u901a\u5e38\u662f\u7531\u65bc\u67e5\u8a62\u8fd4\u56de\u591a\u65bc\u4e00\u884c\u7684\u6578\u64da\u800c\u5c0e\u81f4\u7684\u3002\u901a\u904e\u4f7f\u7528LIMIT\u5b50\u53e5\u3001\u805a\u5408\u51fd\u6578\u3001\u6aa2\u67e5\u67e5\u8a62\u689d\u4ef6\u6216\u4f7f\u7528\u5b50\u67e5\u8a62\u7b49\u65b9\u6cd5\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u4fee\u5fa9\u9019\u500b\u932f\u8aa4\u3002\u4e86\u89e3\u5982\u4f55\u8655\u7406\u9019\u985e\u932f\u8aa4\u5c0d\u65bc\u958b\u767c\u8005\u4f86\u8aaa\u662f\u975e\u5e38\u91cd\u8981\u7684\uff0c\u9019\u4e0d\u50c5\u80fd\u63d0\u9ad8\u6578\u64da\u5eab\u64cd\u4f5c\u7684\u6548\u7387\uff0c\u9084\u80fd\u589e\u5f37\u61c9\u7528\u7a0b\u5e8f\u7684\u7a69\u5b9a\u6027\u3002<\/p>\n
\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 \u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u9700\u6c42\u7684\u5ba2\u6236\u3002\u7121\u8ad6\u662f\u6578\u64da\u5eab\u7ba1\u7406\u9084\u662f\u7db2\u7ad9\u6258\u7ba1\uff0c\u6211\u5011\u7684 \u4f3a\u670d\u5668<\/a> \u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"\u4fee\u5fa9MySQL\u932f\u8aa41172\uff08ER_TOO_MANY_ROWS\uff09\u7684\u65b9\u6cd5\uff0c\u89e3\u6c7a\u67e5\u8a62\u8fd4\u56de\u591a\u65bc\u4e00\u884c\u6578\u64da\u7684\u554f\u984c\uff0c\u78ba\u4fdd\u7d50\u679c\u96c6\u6b63\u78ba\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-177603","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/177603","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=177603"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/177603\/revisions"}],"predecessor-version":[{"id":177604,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/177603\/revisions\/177604"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=177603"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=177603"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=177603"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}