Which statement is better?

Question

I have a statement which i could write in two formats as below,
and I wonder which one is better?
first :
select type, (case type when '01' then 'looking'
                        when '02' then 'for'
                        when '03' then 'help' end case)  as desc
from ( select (case
                        when substr(code, -5, 2)  in ('aa', 'ab') then '01'
                        when substr(code, -5, 2)  in ('ba', 'bb') then '02'
                       when substr(code, -5, 2)  in ('ca', 'cb') then '03'
                  end case ) as type
         from mytable);second:
select (case
                        when substr(code, -5, 2)  in ('aa', 'ab') then '01'
                        when substr(code, -5, 2)  in ('ba', 'bb') then '02'
                       when substr(code, -5, 2)  in ('ca', 'cb') then '03'
                  end case ) as type,
            (case
                        when substr(code, -5, 2)  in ('aa', 'ab') then  'looking'
                        when substr(code, -5, 2)  in ('ba', 'bb') then 'for'
                       when substr(code, -5, 2)  in ('ca', 'cb') then  'help'
                  end case ) as desc,                
         from mytable;this is just an example and in my real statement, there will be 20-30 substr() used.
Thanks

Answer 1

Well you can minimise the number of times you substr to just the once if you want...
select type
      ,decode(type,'01','looking','02','for','03','help') as desc
from (select decode(substr(code, -5, 1),'a','01','b','02','c','03') as type
      from   mytable);
/or
select decode(type,'a','01','b','02','c','03') as type
      ,decode(type,'a','looking','b','for','c','help') as desc
from (select substr(code, -5, 1) as type from mytable);
/... but without more information (like data and expected results) it's difficult to know exactly what would be the best way.