{"id":177933,"date":"2024-11-08T16:46:31","date_gmt":"2024-11-08T08:46:31","guid":{"rendered":"https:\/\/server.hk\/cnblog\/177933\/"},"modified":"2024-11-08T16:46:31","modified_gmt":"2024-11-08T08:46:31","slug":"%e5%a6%82%e4%bd%95%e4%bf%ae%e5%be%a9mysql%e9%8c%af%e8%aa%a41248-sqlstate-42000-er_derived_must_have_alias-%e6%af%8f%e5%80%8b%e8%a1%8d%e7%94%9f%e8%a1%a8%e5%bf%85%e9%a0%88%e6%9c%89%e8%87%aa","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/177933\/","title":{"rendered":"\u5982\u4f55\u4fee\u5fa9MySQL\u932f\u8aa41248 – SQLSTATE: 42000 (ER_DERIVED_MUST_HAVE_ALIAS) \u6bcf\u500b\u884d\u751f\u8868\u5fc5\u9808\u6709\u81ea\u5df1\u7684\u5225\u540d"},"content":{"rendered":"

\u5982\u4f55\u4fee\u5fa9MySQL\u932f\u8aa41248 – SQLSTATE: 42000 (ER_DERIVED_MUST_HAVE_ALIAS)<\/h1>\n

\u5728\u4f7f\u7528MySQL\u9032\u884c\u6578\u64da\u5eab\u64cd\u4f5c\u6642\uff0c\u958b\u767c\u8005\u53ef\u80fd\u6703\u9047\u5230\u5404\u7a2e\u932f\u8aa4\uff0c\u5176\u4e2d\u4e4b\u4e00\u5c31\u662f\u932f\u8aa41248\uff0c\u8a72\u932f\u8aa4\u7684\u63d0\u793a\u4fe1\u606f\u70ba\u201c\u6bcf\u500b\u884d\u751f\u8868\u5fc5\u9808\u6709\u81ea\u5df1\u7684\u5225\u540d\u201d\u3002\u9019\u500b\u932f\u8aa4\u901a\u5e38\u51fa\u73fe\u5728\u4f7f\u7528\u884d\u751f\u8868\uff08Derived Table\uff09\u6642\uff0c\u7576\u4f60\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u4e86\u884d\u751f\u8868\u537b\u6c92\u6709\u70ba\u5176\u6307\u5b9a\u5225\u540d\u6642\uff0c\u5c31\u6703\u5c0e\u81f4\u9019\u500b\u932f\u8aa4\u7684\u767c\u751f\u3002<\/p>\n

\u4ec0\u9ebc\u662f\u884d\u751f\u8868\uff1f<\/h2>\n

\u884d\u751f\u8868\u662f\u6307\u5728SQL\u67e5\u8a62\u4e2d\u4f7f\u7528\u7684\u5b50\u67e5\u8a62\uff0c\u9019\u4e9b\u5b50\u67e5\u8a62\u53ef\u4ee5\u5728FROM\u5b50\u53e5\u4e2d\u4f5c\u70ba\u8868\u4f86\u4f7f\u7528\u3002\u884d\u751f\u8868\u7684\u4e3b\u8981\u4f5c\u7528\u662f\u5c07\u8907\u96dc\u7684\u67e5\u8a62\u5206\u89e3\u70ba\u66f4\u7c21\u55ae\u7684\u90e8\u5206\uff0c\u5f9e\u800c\u63d0\u9ad8\u67e5\u8a62\u7684\u53ef\u8b80\u6027\u548c\u53ef\u7dad\u8b77\u6027\u3002<\/p>\n

\u932f\u8aa41248\u7684\u539f\u56e0<\/h2>\n

\u7576\u4f60\u5728SQL\u67e5\u8a62\u4e2d\u4f7f\u7528\u884d\u751f\u8868\u6642\uff0cMySQL\u8981\u6c42\u6bcf\u500b\u884d\u751f\u8868\u5fc5\u9808\u6709\u4e00\u500b\u5225\u540d\u3002\u9019\u662f\u56e0\u70ba\u5728SQL\u6a19\u6e96\u4e2d\uff0c\u884d\u751f\u8868\u88ab\u8996\u70ba\u4e00\u500b\u81e8\u6642\u8868\uff0c\u5fc5\u9808\u80fd\u5920\u901a\u904e\u5225\u540d\u4f86\u5f15\u7528\u5b83\u3002\u5982\u679c\u6c92\u6709\u70ba\u884d\u751f\u8868\u6307\u5b9a\u5225\u540d\uff0cMySQL\u5c07\u7121\u6cd5\u8b58\u5225\u8a72\u8868\uff0c\u5f9e\u800c\u5f15\u767c\u932f\u8aa41248\u3002<\/p>\n

\u5982\u4f55\u4fee\u5fa9\u932f\u8aa41248<\/h2>\n

\u8981\u4fee\u5fa9\u9019\u500b\u932f\u8aa4\uff0c\u4f60\u53ea\u9700\u70ba\u884d\u751f\u8868\u6307\u5b9a\u4e00\u500b\u5225\u540d\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\uff0c\u5c55\u793a\u4e86\u5982\u4f55\u6b63\u78ba\u4f7f\u7528\u884d\u751f\u8868\u4e26\u70ba\u5176\u6307\u5b9a\u5225\u540d\uff1a<\/p>\n

SELECT derived_table.column_name\nFROM (SELECT column_name FROM table_name) AS derived_table;<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6211\u5011\u5275\u5efa\u4e86\u4e00\u500b\u884d\u751f\u8868\uff0c\u4e26\u70ba\u5176\u6307\u5b9a\u4e86\u5225\u540d\u201cderived_table\u201d\u3002\u9019\u6a23\uff0c\u7576\u6211\u5011\u5728\u5916\u90e8\u67e5\u8a62\u4e2d\u5f15\u7528\u9019\u500b\u884d\u751f\u8868\u6642\uff0c\u5c31\u4e0d\u6703\u51fa\u73fe\u932f\u8aa41248\u4e86\u3002<\/p>\n
\u793a\u4f8b\u5206\u6790<\/h2>\n
\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba\u201cemployees\u201d\u7684\u8868\uff0c\u4e26\u4e14\u6211\u5011\u60f3\u8981\u67e5\u8a62\u6240\u6709\u54e1\u5de5\u7684\u5e73\u5747\u85aa\u8cc7\u3002\u4ee5\u4e0b\u662f\u53ef\u80fd\u5c0e\u81f4\u932f\u8aa41248\u7684\u67e5\u8a62\uff1a<\/p>\n
SELECT avg_salary\nFROM (SELECT AVG(salary) AS avg_salary FROM employees);<\/code><\/pre>\n
\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u6c92\u6709\u70ba\u884d\u751f\u8868\u6307\u5b9a\u5225\u540d\uff0c\u56e0\u6b64\u6703\u5f15\u767c\u932f\u8aa4\u3002\u4fee\u6b63\u5f8c\u7684\u67e5\u8a62\u61c9\u8a72\u5982\u4e0b\uff1a<\/p>\n
SELECT avg_salary\nFROM (SELECT AVG(salary) AS avg_salary FROM employees) AS salary_table;<\/code><\/pre>\n
\u5728\u9019\u88e1\uff0c\u6211\u5011\u70ba\u884d\u751f\u8868\u6307\u5b9a\u4e86\u5225\u540d\u201csalary_table\u201d\uff0c\u9019\u6a23\u5c31\u53ef\u4ee5\u6210\u529f\u57f7\u884c\u67e5\u8a62\uff0c\u800c\u4e0d\u6703\u51fa\u73fe\u932f\u8aa41248\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
MySQL\u932f\u8aa41248\u662f\u7531\u65bc\u5728\u4f7f\u7528\u884d\u751f\u8868\u6642\u672a\u6307\u5b9a\u5225\u540d\u6240\u5f15\u8d77\u7684\u3002\u901a\u904e\u70ba\u6bcf\u500b\u884d\u751f\u8868\u63d0\u4f9b\u4e00\u500b\u660e\u78ba\u7684\u5225\u540d\uff0c\u53ef\u4ee5\u6709\u6548\u907f\u514d\u9019\u500b\u932f\u8aa4\u3002\u5728\u9032\u884c\u8907\u96dc\u67e5\u8a62\u6642\uff0c\u5408\u7406\u4f7f\u7528\u884d\u751f\u8868\u548c\u5225\u540d\u4e0d\u50c5\u80fd\u63d0\u9ad8\u67e5\u8a62\u7684\u53ef\u8b80\u6027\uff0c\u9084\u80fd\u63d0\u5347\u6578\u64da\u5eab\u64cd\u4f5c\u7684\u6548\u7387\u3002<\/p>\n
\u5982\u679c\u60a8\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\u7528\u6236\u7684\u9700\u6c42\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\u8aa41248\u7684\u65b9\u6cd5\uff0c\u4e86\u89e3\u5982\u4f55\u70ba\u6bcf\u500b\u884d\u751f\u8868\u6dfb\u52a0\u5225\u540d\u4ee5\u89e3\u6c7aSQLSTATE: 42000 (ER_DERIVED_MUST_HAVE_ALIAS)\u554f\u984c\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-177933","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/177933","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=177933"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/177933\/revisions"}],"predecessor-version":[{"id":177934,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/177933\/revisions\/177934"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=177933"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=177933"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=177933"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}