temp:='3'
table.filter:='id='''+temp+'''';
table.filtered:=true;
combobox1.items.clear;
for i:=0 to table.recordcount-1 do
begin
if combobox.items.indexof(table.fielbyname('myfield').asstring)=-1 then
combobox.items.add(table.fieldbyname('myfield').asstring);
table.next;
end;