Sql 子查询除以计数（*）

我正在运行一个查询，并尝试获取数据库中失败与成功的返回百分比

SELECT ((SELECT count(*) FROM validation WHERE request_date BETWEEN (SYSDATE - 30/(24*60)) AND SYSDATE AND response != 'VERIFIED') / count(*))
AS percentage
FROM (SELECT * FROM validation
WHERE request_date BETWEEN (SYSDATE - 30/(24*60)) AND SYSDATE)
;

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它返回错误“ORA-00937：不是单个组函数”。我本以为子查询将返回一个值，因此我可以简单地将其除以计数（*）。有什么想法吗？

您可能只需要从dual中获得两个子查询

 Select 
   (SELECT count(*) FROM validation WHERE request_date BETWEEN (SYSDATE - 30/(24*60)) AND SYSDATE AND response != 'VERIFIED')/
   (SELECT count(*) FROM validation WHERE request_date BETWEEN (SYSDATE - 30/(24*60)) AND SYSDATE)
 from dual;

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你把问题复杂化了。您不需要任何子查询：

select count(case when response != 'VERIFIED' then 'X' end) / count(*) as percentage
  from validation
 where request_date BETWEEN (SYSDATE - 30/(24*60)) AND SYSDATE

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就我个人而言，我认为编写查询的最佳方式是：

select avg(case when response <> 'VERIFIED' then 1.0 else 0 end) as percentage
from validation v
where request_date BETWEEN (SYSDATE - 30/(24*60)) AND SYSDATE;

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对甲骨文来说，这仍然是一个难点，我从未想过在计数函数中放入case语句。谢谢你的提示！嘿，伙计，我想你可以这样做，但我觉得我不需要这样做。

where request_date between sysdate - interval '30' minute and sysdate