跳异常:Error Creating Cursor Handle

很简单的代码:
    query1.Close;
    query1.SQL.Text := 'declare @top integer' + #13#10
            + 'select @top = 1' + #13#10
            + 'select @top';
    query1.Open;
如改为:
    query1.SQL.Text := 'declare @top integer' + #13#10
            //+ 'select @top = 1' + #13#10
            + 'select @top';
    query1.Open;
则不会跳异常.
请高手帮忙,谢谢