SQL使用分组值在子查询+“where in（））”中使用

Question

我有下表：

Case with columns > ID,ResponsibleID
Action with columns > ID,CaseID,Action

我希望得到一份所有责任人的清单，列出所有案件数量及其在所有案件中的总行动次数。

这可能是查询是否有效，但它不是

Select 
    Case.ResponsibleID,
    CaseCount=count(*),
    --how can i tell sql that this is the CaseID sublist of the group?
    --It would be possible with a subquery, but i rather not do that for performance reasons. 
    --the real query gets the caseID list from a table 3 or 4 joins later.
    ActionCount=(select count(*) from Action where CaseID in Case.CaseID) 
From Case
Group by ResponsibleID

Answer 1

SELECT  c.ResponsibleID
        , COUNT(DISTINCT c.ID)
        , COUNT(*)
FROM    Case c
        LEFT JOIN Action a ON a.CaseID = c.CaseID
GROUP BY
        c.ResponsibleID