postgresql - Postgre SQL incorrect syntaxt near If -

i'm trying create function it's having error @ if statement don't know what's problem it.

create function uspgetcountrylistwithpagenumber(in "pagenumber" integer, in "pagesize"         integer, in "whereclause" text, in "orderby" text) returns setof getcountrylistitem $body$declare  rowdata "getcountrylistitem"%rowtype;      if $1 <> -1 , $2 <> -1          rowdata in         loop             execute 'select "countryid","countryname"' ||                     'from "mastercountry"' ||                     $3 ||                      $4 ||                     'limit' || $2 ||                     'offset' || ($1-1)*$2                        return next rowdata;         end loop;         return;          else         rowdata in         loop             execute 'select "countryid","countryname"' ||                     'from "mastercountry"' ||                     'order "countryname" asc'             return next rowdata;             end loop;             return;     end if; end; $body$ language plpgsql immutable; alter function public.uspgetcountrylistwithpagenumber(in integer, in integer, in text, in text) owner postgres; 

what want achieve custom paging .. want have function can take pagenumber,pagesize,whereclause,and orderbyclause

pagenumber=1 pagesize=10 whereclause=where 1=1 , countryname='india' orderbyclause=order countryname desc 

above parameter values can helpful solving problem let me know if more information required. thank in advance..:p

you need begin before first if.