SQL使用分組值在子查詢+「其中（））列」

Question

我有如下因素表使用方法：

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

我想所有responsibles的列表以及它們病例數和他們的所有這些案件的總行動數量。

這可能是查詢，如果它的工作，但它並不

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