请问如何用sql语句将3行数据合并为1行数据？

Question

SQL> desc a5;
 名称                                      是否为空? 类型
 ----------------------------------------- -------- ------------- A                                                  VARCHAR2(5)
 B                                                  VARCHAR2(5)
 C                                                  VARCHAR2(5)
 ID                                                 VARCHAR2(5)SQL> select * from a5;A     B     C     ID
----- ----- ----- -----
1                  a
      2            a
            3      a
4                  b
      5            b也就是说，id为a的数据行，只有1个列有值，而且没有重复。我想处理为如下的样子SQL> select * from a5;A     B     C     ID
----- ----- ----- -----
1     2     3      a
4     5            b

Answer 1

select sum(NVL(A,0)) as A, sum(NVL(B,0)) as B, sum(NVL(C,0)) as C, ID from a5 group by ID

Answer 2

select sum(A) A , sum(B) B , sum(C) c from tb group by id