Oracle SQL子查询错误

我试图写一个子查询到左联接表，但我有错误，需要帮助找出我的错误，谢谢

select IT.*,
(select  firstname,lastname,sum(cost) as 2016_cost,agencyname
from sheet1
group by firstname,lastname,agencyname as aa)
from IT
left join aa on IT.lastname=aa.lastname,IT.firstname=aa.lastname

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看起来你想要这个：

SELECT IT.*, aa.firstname, aa.lastname, aa.2016_cost, aa.agencyname
FROM IT
LEFT JOIN (SELECT firstname, lastname, sum(cost) as 2016_cost, agencyname
           FROM sheet1
           GROUP BY firstname, lastname, agencyname
          ) as aa on IT.lastname = aa.lastname
                 and IT.firstname = aa.lastname

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代码中的子查询位于

SELECT

中，您可以在其中放置一个列级子查询。您似乎想要一个表子查询或派生表，它应该放在您的

FROM/JOIN

列表中。

这是什么错误？顺便说一句，GROUPBY part中的“as aa”在我看来是不正确的