SQL> with t (model, speed, ram, hd, cd, price) as
  2  (
  3  select 1,100,8,100gb,'yes',150 from dual
  4  )
  5  select* from t
  6  UNPIVOT (value FOR chr IN (model, speed, ram, hd, cd, price))
  7  /
 
with t (model, speed, ram, hd, cd, price) as
(
select 1,100,8,100gb,'yes',150 from dual
)
select* from t
UNPIVOT (value FOR chr IN (model, speed, ram, hd, cd, price))
 
ORA-01790: expression must have same datatype as corresponding expression
 
SQL> 
SQL> 
SQL> 
SQL> with t(model,speed,ram,hd,cd,price) as
  2   (select 1, 100, 8, '100gb', 'yes', 150
  3      from dual)
  4  select * from (
  5  select to_char(model) model, to_char(speed) speed, to_char(ram) ram, to_char(hd) hd, to_char(cd) cd, to_char(price)price
  6   from t
  7   )
  8   UNPIVOT(value FOR chr IN(model, speed, ram, hd, cd, price))
  9  /
 
CHR   VALUE
----- -----
MODEL 1
SPEED 100
RAM   8
HD    100gb
CD    yes
PRICE 150
 
6 rows selected
 
SQL>