請求一段SQL語句(急！！！！！！！！！)

Question

實現如下功能：
  有一個TABLE 
  欄位：   RMA_NO        SSN       Is_Closed
  記錄：   Rma001        ss1        1
           Rma001        ss2        0
           Rma001        ss3        2想得到的查詢結果如下：
           Rma_no     Count_1(Is_closed=1)    Count_0(Is_closed=0)        Count_2
           Rma001     1                        1                          1來者有份......

Answer 1

select Rma_no,sum(decode(Is_Closed,1,1,0)) count_1,
       sum(decode(Is_Closed,0,1,0)) count_0,
       sum(decode(Is_Closed,2,1,0)) count_2
from   TABLE 
group by Rma_no