sql语句优化

Question

select c.OrderID,cp.MemberNo,sum(isnull(cp.PaymentPrice,0)) PaymentPrice,cp.CurrencyCode,SupplierSettlement  from Client_Orders c 
left join dbo.CP_Records cp on c.OrderID=cp.OrderID  
left join Purchase_Orders p on c.OrderID=p.OrderID and p.IFAvailable=0 
where c.OrderStates='8' and SupplierSettlement=1 and (Type=2 or Type=4) 
group by c.OrderID,cp.MemberNo,cp.CurrencyCode,SupplierSettlement 
having sum(isnull(cp.PaymentPrice,0))<0 
union 
select c.OrderID,cp.MemberNo,sum(isnull(cp.PaymentPrice,0)) PaymentPrice,cp.CurrencyCode,SupplierSettlement from Client_Orders c 
left join dbo.CP_Records cp on c.OrderID=cp.OrderID 
left join dbo.Purchase_Orders p on c.OrderID=p.OrderID and p.IFAvailable=0 
where (Type=2 or Type=4) and SupplierSettlement=1 
group by c.OrderID,Reserve,ResAdditional,cp.MemberNo,cp.CurrencyCode,SupplierSettlement
having (sum(isnull(cp.PaymentPrice,0)*-1)-(Reserve+ResAdditional))>0 

Answer 1

可以用下
  WITH AS短语 试试

Answer 2

查看SQL执行计划..

Answer 3

1：索引优化http://www.cnblogs.com/worfdream/articles/2840582.html
2：查看执行计划