function CF_1Formula return Number as
a  number;
begin
	a :=:sal+:comm;
	if a=null then
  return (o);
	else
		return (a);
end
REP-737: Should be a function with return type '<returntype>'.

function CF_1Formula return Number as
A  number;
B Number;
begin
	A :=Nvl(:sal,0)+ Nvl(:comm,0);

	IF ( A is Null or A=0 ) then
            B:=0;
        Else
            B:= A;
        END IF;
        
        Return B;
       
end

if a = null then

if a is null then

function CF_1Formula return Number as
begin
  return case when :sal + :comm is null then 0
              else :sal + :comm
         end;
end;