Helping in long decode

Question

Hello world,
i have a problem,
i created a form and inside it in program unit i created code with decode,
the probem i want to add more option inside decode for filtering but you know my decode very long and complex
for example ,
sum(decode(classnum,'01',nvl(mark,0))
i dont want to add more option as
sum(decode(classnum,'01',nvl(mark,0),'03',nvl(mark,0))
and grouping by classnum,
i want just take full code
for example
this code
sum(decode(classnum,'01',nvl(mark,0))
i just want to take it copy and change the option
sum(decode(classnum,'03',nvl(mark,0))
to be
sum(decode(classnum,'01',nvl(mark,0))
sum(decode(classnum,'03',nvl(mark,0))
and go on

Answer 1

Formatting the decode can make it readable and show the intent clearer.
sum(decode(classnum,'01', mark
                   ,'02', mark
                   ,'03', mark
                   ,'04', mark))Also, you may be able to case/when:
sum(case when classnum in('01', '02', '03','04') then mark end)In case the conditonal summation is common to your application you can even put the logic inside a lookup table:
create table sum_class(
   classnum varchar2(2)
  ,sumthis varchar2(1)
insert into sum_class values('01', 'Y');
insert into sum_class values('02', 'Y');
insert into sum_class values('03', 'Y');
insert into sum_class values('04', 'Y');
insert into sum_class values('05', 'Y');
insert into sum_class values('06', 'N');
select sum(case when sumthis = 'Y' then mark end)
  from yourtable left outer join sum_class using(classnum)Note, all code is untested.
/ Ronnis