Oracle 实现行列转换

SQL> DESC TEST  测试表:        Name    Type            Nullable    Default Comments
       ----     ------------         --------      -------     --------
       A        NUMBER           Y                        
       B        VARCHAR2(20) Y          SQL> select * from test;                  A B
       ---------- --------------------
                 1 a
                 1 b
                 1 c
                 1 d
                 1 e
                 2 a
                 2 b
                 3 a