列行转换

SQL> select * from col_row_test;

NAM       VAL1       VAL2       VAL3
--- ---------- ---------- ----------
a            1          2          3
b            1          2          3
c            1          2          3
d            1          2          3

结果

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

 

select max(a) a, max(b) b, max(c) c, max(d) d
  from (select decode(nam, 'a', val1, '') a,
               decode(nam, 'b', val1, '') b,
               decode(nam, 'c', val1, '') c,
               decode(nam, 'd', val1, '') d
          from col_row_test)
union
select max(a), max(b), max(c), max(d) d
  from (select decode(nam, 'a', val2, '') a,
               decode(nam, 'b', val2, '') b,
               decode(nam, 'c', val2, '') c,
               decode(nam, 'd', val2, '') d
          from col_row_test)
union
select max(a), max(b), max(c), max(d) d
  from (select decode(nam, 'a', val3, '') a,
               decode(nam, 'b', val3, '') b,
               decode(nam, 'c', val3, '') c,
               decode(nam, 'd', val3, '') d
          from col_row_test)