create or replace function ListFirst
(
 source IN long,
 delim IN varchar2
)
RETURN long IS
pos number;
templist long;
BEGIN
templist := source;
pos:=instr(templist,delim);
if (pos = 1) then -- clean delimiter from first character in list
  templist:=substr(templist,pos+1);  
end if;
if (delim = substr(templist,length(templist),1)) then -- clean delimiter from end
  templist:=substr(templist,1,length(templist)-1);  
end if;
pos:=instr(templist,delim);
   if pos != 0 then
     if pos != 1 then
        return substr(templist,1,pos-1);
       else
        return null;
     end if;
    else
     if (length(templist)>0) then
       return templist;
      else
       return null;
     end if;  
   end if;
end ListFirst; 
/
show errors;