ขอความช่วยเหลือครับ เพิ่งหัดใหม่ ใช้ DatePicker เพื่อเป็นเงื่อนไข Select Date/time ในคำสั่ง SQL ไม่ได้ครับ สงสัยว่าเป็นที่ formate วันเวลา แต่แก้ไม่ถูกครับ

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace TestConnectSQL
{
    public partial class Form2 : Form
    {
        SqlDataAdapter sda;
        SqlCommandBuilder scb;
        DataTable dt;
        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
           
        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
        {

        }

        private void btnOK_Click(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection("Data Source=LENOVO\\SQLEXPRESS;Initial Catalog=ContinuumDB;Persist Security Info=True;User ID=Andover97;Password=Pyramid97");
            sda = new SqlDataAdapter(@"SELECT       AccessEvent.TimeStamp,AccessEvent.CardType, AccessEvent.SiteCode, AccessEvent.Message, AccessEvent.NonABACardNumber, Personnel.FirstName, Personnel.LastName
FROM            AccessEvent INNER JOIN
                         Personnel ON AccessEvent.PersonIdLo = Personnel.ObjectIdLo
WHERE        AccessEvent.TimeStamp BETWEEN '" + dateStart.Value.ToString() + "' AND '" + dateEnd.Value.ToString()+ "'", con);
            dt = new DataTable();
            sda.Fill(dt);
            dataGridView1.DataSource = dt;
        }

        /// <summary>
        /// Exports the datagridview values to Excel.
        /// </summary>
        private void ExportToExcel()
        {
            // Creating a Excel object.
            Microsoft.Office.Interop.Excel._Application excel = new Microsoft.Office.Interop.Excel.Application();
            Microsoft.Office.Interop.Excel._Workbook workbook = excel.Workbooks.Add(Type.Missing);
            Microsoft.Office.Interop.Excel._Worksheet worksheet = null;

            try
            {

                worksheet = workbook.ActiveSheet;

                worksheet.Name = "ExportedFromDatGrid";

                int cellRowIndex = 1;
                int cellColumnIndex = 1;

                //Loop through each row and read value from each column.
                for (int i = 0; i < dataGridView1.Rows.Count - 1; i++)
                {
                    for (int j = 0; j < dataGridView1.Columns.Count; j++)
                    {
                        // Excel index starts from 1,1. As first Row would have the Column headers, adding a condition check.
                        if (cellRowIndex == 1)
                        {
                            worksheet.Cells[cellRowIndex, cellColumnIndex] = dataGridView1.Columns[j].HeaderText;
                        }
                        else
                        {
                            worksheet.Cells[cellRowIndex, cellColumnIndex] = dataGridView1.Rows[i].Cells[j].Value.ToString();
                        }
                        cellColumnIndex++;
                    }
                    cellColumnIndex = 1;
                    cellRowIndex++;
                }

                //Getting the location and file name of the excel to save from user.
                SaveFileDialog saveDialog = new SaveFileDialog();
                saveDialog.Filter = "Excel files (*.xlsx)|*.xlsx|All files (*.*)|*.*";
                saveDialog.FilterIndex = 2;

                if (saveDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                {
                    workbook.SaveAs(saveDialog.FileName);
                    MessageBox.Show("Export Successful");
                }
            }
            catch (System.Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                excel.Quit();
                workbook = null;
                excel = null;
            }
        }

        private void btnExport_Click(object sender, EventArgs e)
        {
            ExportToExcel();
        }

        private void dateTimePicker2_ValueChanged(object sender, EventArgs e)
        {
        
        }

        //********************************************************//
    }
}

/****** Script for SelectTopNRows command from SSMS  ******/
SELECT        AccessEvent.TimeStamp,AccessEvent.CardType, AccessEvent.SiteCode, AccessEvent.Message, AccessEvent.NonABACardNumber, Personnel.FirstName, Personnel.LastName
FROM            AccessEvent INNER JOIN
                         Personnel ON AccessEvent.PersonIdLo = Personnel.ObjectIdLo
WHERE        AccessEvent.TimeStamp BETWEEN '2/10/2018' AND '2/21/2018 11:59:59 PM'

BETWEEN '2/10/2018' AND '2/21/2018 11:59:59 PM'

strSQL1 = "SELECT  * FROM  table WHERE DateTime BETWEEN '" + dateTimePicker1.Value.ToString("MM/dd/yyyy", new CultureInfo("en-US")) + "' AND '" + dateTimePicker2.Value.ToString("MM/dd/yyyy", new CultureInfo("en-US")) + " 11:59:59 PM'"

WHERE        AccessEvent.TimeStamp BETWEEN '" + dateStart.Value.ToString("MM/dd/yyyy", new CultureInfo("en-US")) + "' AND '" + dateEnd.Value.ToString("MM/dd/yyyy hh:mm:ss", new CultureInfo("en-US")) + "11:59:59 PM'", con);

SqlConnection con = new SqlConnection("Data Source=LENOVO\\SQLEXPRESS;Initial Catalog=ContinuumDB;Persist Security Info=True;User ID=Andover97;Password=Pyramid97");
            sda = new SqlDataAdapter(@"SELECT       AccessEvent.TimeStamp,AccessEvent.CardType, AccessEvent.SiteCode, AccessEvent.Message, AccessEvent.NonABACardNumber, Personnel.FirstName, Personnel.LastName
FROM            AccessEvent INNER JOIN Personnel ON AccessEvent.PersonIdLo = Personnel.ObjectIdLo
WHERE        AccessEvent.TimeStamp BETWEEN '" + dateStart.Value.ToString("MM/dd/yyyy", new CultureInfo("en-US")) + "' AND '" + dateEnd.Value.ToString("MM/dd/yyyy hh:mm:ss", new CultureInfo("en-US")) + "'", con);