如何做添加在Sql Server中使用动态生成字段？

Question

我有名为“购物车”的表。字段是：

• CartId
• ClientId
• ProductId
• Qty

现在我加入这个表ProductMaster得到ProductName和ProuctPrice

select cc.CartId,cc.ProductId,pm.ProductName,cc.Qty, 
     (pm.ProductPrice * cc.Qty) As SubTotal 
from ClientCart as cc 
    inner join ProductMaster as pm on cc.ProductId = pm.ProductId 

现在我想生成GrandTotal使用动态字段SubTotal。我怎样才能做到这一点？

Answer 1

with CTE as 
(
select cc.CartId,cc.ProductId,pm.ProductName,cc.Qty, 
     (pm.ProductPrice * cc.Qty) As SubTotal 
from ClientCart as cc 
    inner join ProductMaster as pm on cc.ProductId = pm.ProductId 
where cc.ClientId = @id 
) 
select * 
from CTE 
union 
select null,null, null,null, sum(SubTotal) -- this is a grand total of all sub totals 
from CTE 

这不是正确的汇总方法，但也不是你的所以这将很好地工作

Answer 2

试试这个：

select subtable.CartId, sum(subtable.SubTotal) 
from (
select cc.CartId,cc.ProductId,pm.ProductName,cc.Qty, 
     (pm.ProductPrice * cc.Qty) As SubTotal 
from ClientCart as cc 
inner join ProductMaster as pm on cc.ProductId = pm.ProductId 
where cc.ClientId = @id) subtable 
group by subtable.CartId;