比较SQL select语句c＃中的多个数组值

Question

我忙于c＃windows窗体中的任务程序。我编写了一个应该完成这项工作的代码，但不知怎的。在第一个foreach语句中，他停止执行该方法。

这是我的代码：

        int userid = 1;
        MySqlCommand mscSelectId = new MySqlCommand("SELECT * FROM pakket WHERE                 gebruikersid=@userid", _msConnection);
        mscSelectId.Parameters.AddWithValue("@userid", userid);
        MySqlDataReader msSelectid = mscSelectId.ExecuteReader();
        DataTable dtSelectId = new DataTable();
        dtSelectId.Load(msSelectid);

        string[] saAllid = new string[dtSelectId.Rows.Count + 1];



        int a = 0;
        foreach (DataRow row in dtSelectId.Rows)
        {
            saAllid[a] = (string)row["groepsid"];
            a++;
        }

        int b = 0;

        int c = 0;

        foreach (string item in saAllid)
        {
            MySqlCommand mscSelectGroep = new MySqlCommand("SELECT * FROM groep WHERE id=@groepsid", _msConnection);
            mscSelectGroep.Parameters.AddWithValue("@groepsid", saAllid[b]);
            MySqlDataReader msSelectedGroep = mscSelectGroep.ExecuteReader();
            DataTable dtSelectGroep = new DataTable();
            dtSelectGroep.Load(msSelectedGroep);

            b++;

            saGroepNaam = new string[dtSelectGroep.Rows.Count + 1];

            foreach (DataRow row in dtSelectGroep.Rows)
            {
                saGroepNaam[c] = (string)row["groepsnaam"];
                c++;
            }
        }

        int d = 0;

        int mtop = 10;
        int mleft = 15;
        int count = 1;

        List<Label> _lListGroep = new List<Label>();

        foreach (string item in  saGroepNaam)
        {
            Label temp = new Label();
            temp.Name = "lb" + d;
            temp.Text = saGroepNaam[d];
            temp.Width = 285;
            temp.Height = 20;
            temp.Left = 5;
            temp.Top = mtop;
            temp.BorderStyle = BorderStyle.Fixed3D;

            mleft += 5;

            if (count == 1)
            {
                mtop += 25;
                mleft = 5;
                count = 0;
            }
            count++;
            d++;
            _lListGroep.Add(temp);
        }

        return _lListGroep.ToArray();

感谢您的帮助