ช่วยดูด้วยครับ Checked Listbox คือว่าปัญหาที่เกิดคือ มันแสดงเป็น system.data.datarowview อยากให้แสดงที่เลือกเป็น IDBookType

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using books.Class;

namespace books
{
    public partial class Form1 : Form
    {
        SqlConnection Conn;
        SqlCommand com;
        SqlDataReader dr;
        DataTable dtBookType;
        StringBuilder sb;
    

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            string strConn;
            strConn = DBConnString.strConn;
            Conn = new SqlConnection();
            if (Conn.State == ConnectionState.Open)
            {
                Conn.Close();
            }
            Conn.ConnectionString = strConn;
            Conn.Open();
            sb = new StringBuilder();

            sb.Append("SELECT * FROM BookType ORDER BY IDBookType;");
            string sqlIni;
            sqlIni = sb.ToString();
            com = new SqlCommand();
            com.CommandText = sqlIni;
            com.CommandType = CommandType.Text;
            com.Connection = Conn;
            dr = com.ExecuteReader();

            if (dr.HasRows)
            {

                dtBookType = new DataTable();
                dtBookType.Load(dr);
                checkedListBox1.BeginUpdate();
                checkedListBox1.DataSource = dtBookType;
                checkedListBox1.DisplayMember = "NameBookType";
                checkedListBox1.ValueMember = "IDBookType";
                checkedListBox1.CheckOnClick = true;
                checkedListBox1.EndUpdate();

            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
             string ListChecked = "";
            foreach (object itm in checkedListBox1.CheckedItems)
            {
                ListChecked += itm.ToString();
            }
            MessageBox.Show("You choose: " +ListChecked , "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
           
        }
    }
}