如何将sql查询的结果保存到lazarus中的变量中？

var
  Query: TSQLQuery;
  ResultValue: Integer;
begin
  Query := TSQLQuery.Create(nil);
  try
    Query.SQL.Text := 'SELECT COUNT(*) FROM TableName';
    Query.Open;
    ResultValue := Query.Fields[0].AsInteger;
  finally
    Query.Free;
  end;
end;