qual campo é a primary Key da tabela

function GetFielKey(var ACon: TZConnection; const ATableName: string): string;
var
   qry: TZQuery;
begin
   qry := TZQuery.Create(nil);
   try

      qry.Connection := ACon;
      qry.SQL.Text   := ´describe ´ + ATableName;
      ACon.Connect;
      qry.Open;

      while not qry.Eof do
      begin
         if qry.FieldByName(´Key´).AsString = ´PRI´ then
         begin
            Result := Trim(qry.FieldByName(´Field´).AsString);
            Break;
         end;

         qry.Next;

      end;
   finally
      qry.Free;
   end;
end;