一个Left Join 问题，请大家帮忙！(20分)

select Distinct C.A01,C.A02,A.A08,Isnull(A.A06,0) as A,Isnull(B.A06,0) as B,Isnull(A.A06,0)+Isnull(B.A06,0) As SS
From B1010 C
Left Join
(
Select A08,A02,A01,Sum(Isnull(A06,0)) As A06 from B1010
Where (A05='组立工时') and (A07>='2006/01/01') and (A07<='2006/02/14') Group By A08,A02,A01
) A On C.A08=A.A08 And A.A01=C.A01 And A.A02=C.A02
Left Join
(
Select A08,A02,A01,Sum(Isnull(A06,0)) As A06 from B1010
Where (A05='设计工时') and (A07>='2006/01/01') and(A07<='2006/02/14') Group By A08,A02,A01
) B On C.A08=B.A08 And B.A01=C.A01 And B.A02=C.A02
Where Isnull(A.A06,0)+ Isnull(B.A06,0)<>0
order by C.A01,C.A02,A.A08