在发个实用的行列转换

SQL> desc row_col_test
Name Type    Nullable Default Comments
---- ------- -------- ------- --------
A    INTEGER Y                        
B    INTEGER Y                        
C    INTEGER Y                        
D    INTEGER Y                        
E    INTEGER Y                        

SQL> select * from row_col_test;

 

A  B  C  D  E
-- -- -- -- --
1  1  1  1  1
2  2  2  2  2
3  3  3  3  3

 

其中列E作为标识列，结果：

属性名   MAX(值1)   MAX(值2)   MAX(值3)
------ ---------- ---------- ----------
a               1          2          3
b               1          2          3
c               1          2          3
d               1          2          3

 

select 属性名, max(值1), max(值2), max(值3)
  from (select 'a' 属性名,
               decode(e, 1, a, '') 值1,
               decode(e, 2, a, '') 值2,
               decode(e, 3, a, '') 值3
          from row_col_test)
 group by 属性名
union
select 属性名, max(值1), max(值2), max(值3)
  from (select 'b' 属性名,
               decode(e, 1, b, '') 值1,
               decode(e, 2, b, '') 值2,
               decode(e, 3, b, '') 值3
          from row_col_test)
 group by 属性名
union
select 属性名, max(值1), max(值2), max(值3)
  from (select 'c' 属性名,
               decode(e, 1, c, '') 值1,
               decode(e, 2, c, '') 值2,
               decode(e, 3, c, '') 值3
          from row_col_test)
 group by 属性名
union
select 属性名, max(值1), max(值2), max(值3)
  from (select 'd' 属性名,
               decode(e, 1, d, '') 值1,
               decode(e, 2, d, '') 值2,
               decode(e, 3, d, '') 值3
          from row_col_test)
 group by 属性名