从DataReader正确加载DataGridView

Question

阅读this文档我认为以下代码无效：

    using (SqlConnection con = new SqlConnection(Properties.Settings.Default.C_Str))
    {
        try
        {
            using (SqlCommand cmd = new SqlCommand("PerformSearch", con))
            {
                cmd.CommandType = CommandType.StoredProcedure;
                string SearchString = textBoxSearchSting.Text;
                cmd.Parameters.Add("SearchString", SqlDbType.VarChar).Value = SearchString;

                con.Open();

                dataGridView1.DataSource = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            }
        }
        catch (Exception) { throw; }
        finally { con.Close(); }
    }

或者我至少可以使用以下内容：

        using (SqlConnection con = new SqlConnection(Properties.Settings.Default.C_Str))
        {
            try
            {
                using (SqlCommand cmd = new SqlCommand("PerformSearch", con))
                {
                    cmd.CommandType = CommandType.StoredProcedure;
                    string SearchString = textBoxSearchSting.Text;
                    cmd.Parameters.Add("SearchString", SqlDbType.VarChar).Value = SearchString;

                    con.Open();

                    SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                    dataGridView1.DataSource = reader;
                }
            }
            catch (Exception) { throw; }
            finally { con.Close(); }
        }

但是上述工作没有。使用下面的代码确实有效，使用相同的搜索值，下面是用我的查询填充datagridview的最佳方法吗？为什么上述任何一种都不起作用？

        using (SqlConnection con = new SqlConnection(Properties.Settings.Default.C_Str))
        {
            try
            {
                using (SqlCommand cmd = new SqlCommand("PerformSearch", con))
                {
                    cmd.CommandType = CommandType.StoredProcedure;
                    string SearchString = textBoxSearchSting.Text;
                    cmd.Parameters.Add("SearchString", SqlDbType.VarChar).Value = SearchString;

                    con.Open();                           

                    DataTable dt = new DataTable();
                    dt.Load(cmd.ExecuteReader(CommandBehavior.CloseConnection));

                    if (dt.Rows.Count > 0 && dt != null)
                    {
                        dataGridView1.DataSource = dt;
                    }
                }
            }
            catch (Exception) { throw; }
            finally { con.Close(); }
        }

下面也有效，我会因为任何原因更好地使用数据适配器吗？

        using (SqlConnection con = new SqlConnection(Properties.Settings.Default.C_Str))
        {
            try
            {
                using (SqlCommand cmd = new SqlCommand("PerformSearch", con))
                {
                    cmd.CommandType = CommandType.StoredProcedure;
                    string SearchString = textBoxSearchSting.Text;
                    cmd.Parameters.Add("SearchString", SqlDbType.VarChar).Value = SearchString;

                    DataTable dt = new DataTable();

                    using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                    {
                        con.Open();

                        da.Fill(dt);

                        if (dt.Rows.Count > 0 && dt != null)
                        {
                            dataGridView1.DataSource = dt;
                        }
                    }
                }
            }
            catch (Exception) { throw; }
            finally { con.Close(); }
        }