PostgreSQL:在WHERE子句中使用子查询缩写(‘AS’)
发布时间:2020-12-13 16:06:33 所属栏目:百科 来源:网络整理
导读:考虑PostgreSQL中的以下查询: SELECT a,b,(A VERY LONG AND COMPLICATED SUBQUERY) AS c,(ANOTHER VERY LONG AND COMPLICATED SUBQUERY) AS dFROM table 我希望在WHERE子句中有c和d,如: WHERE c AND d; 但是,据我所知,我只能这样做: WHERE A VERY LONG AN
考虑PostgreSQL中的以下查询:
SELECT a,b,(A VERY LONG AND COMPLICATED SUBQUERY) AS c,(ANOTHER VERY LONG AND COMPLICATED SUBQUERY) AS d FROM table 我希望在WHERE子句中有c和d,如: WHERE c AND d; 但是,据我所知,我只能这样做: WHERE A VERY LONG AND COMPLICATED SUBQUERY) AND (ANOTHER VERY LONG AND COMPLICATED SUBQUERY) 这是笨拙的,代码复制,breaking the single-choice principle和完全丑陋. 顺便说一下,同样的问题适用于SELECT子句:我不能将缩写用于先前定义的子查询. 解决方法
您可以使用子查询:
SELECT a,c,d FROM (SELECT a,(ANOTHER VERY LONG AND COMPLICATED SUBQUERY) AS d FROM table ) AS T1 WHERE c AND d 您也可以使用CTE执行此操作. (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |