Given the following SAS data sets:   

  WORK.VISIT1             WORK.VISIT2   

  Id     Expense          Id     Cost   
  —    ——-          —    —-   
  001        500          001     300   
  001        400          002     600   
  003        350

  The following result set was summarized and
  consolidated using the SQL procedure:

  Id     Cost
  —    —-
  001     300
  001     900
  002     600
  003     350

  Which of the following SQL statements was   
  most likely used to generate this result?   
A.
select
   Id,
   sum(Expense) label=’COST’   
from WORK.VISIT1
group by 1   
union all   
select
   Id,
   sum(Cost)
from WORK.VISIT2
group by 1   
order by 1,2
;     

B.
select
   id,
   sum(expense) as COST
from  
   WORK.VISIT1(rename=(Expense=Cost)),  
   WORK.VISIT2
where VISIT1.Id=VISIT2.Id      
group by Id  
order by     
   Id,
   Cost
;     

C.
select
   VISIT1.Id,
   sum(Cost) as Cost   
from  
   WORK.VISIT1(rename=(Expense=Cost)),  
   WORK.VISIT2
where VISIT1.Id=VISIT2.Id      
group by Id  
order by     
   Id,
   Cost
;     

D.
select
   Id,
   sum(Expense) as Cost
from WORK.VISIT1
group by Id  
outer union corr
select
   Id,
   sum(Cost)
from WORK.VISIT2
group by Id  
order by 1,2

大牛们, 有的选a, 有的选d.  正确答案应该是什么?