SQL - 哪个查询更有效？

Question

- 假设样本记录显示CompanyName，CompanyID，OrderID，Ordername，Sum（Amount）。除了所有列都是Varchar

CompanyName  | CompanyID  | OrderID    |  OrderName    |      Amount
CS           |    10      |  5567      |  Bonds        |      67000
CS           |    10      |  5567      |  Bonds        |      77000
CS           |    10      |  5566      |  Derivatives  |      90000
Barleys      |    20      |  5567      |  Bonds        |      90000
Barleys      |    20      |  5566      |  Derivatives  |      90000
T.D          |    30      |  5566      |  Derivatives  |      90000
T.D          |    30      |  5567      |  Bonds        |      60000

哪种查询效率高

Select CompanyName, CompanyID, OrderID, OrderName ,Sum(Amount)
from @Table 
group by CompanyName, CompanyID, OrderID, OrderName;

或者：

Select  CompanyID, Max(CompanyName),OrderID, Max(OrderName) ,Sum(Amount)
from @Table
group by  CompanyID, OrderID;

如果表包含超过700万条记录，那么两个查询都会给出相同的结果但是知道哪个查询在性能方面是好的。该组会影响表现吗？