c# dataGridView update

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C#

WinForms

below is my code but button2_Click(object sender, EventArgs e) is not working, it was supposed to auto update gridview to database. incase its showing error:

Dynamic SQL generation for the UpdateCommand is not supported against a SelectCommand that does not return any key column information.

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

namespace Customer
{
    public partial class frmGridVw : Form
    {
        private String connectionString = null;
        private SqlConnection sqlConnection = null;
        private SqlDataAdapter sqlDataAdapter = null;
        private SqlCommandBuilder sqlCommandBuilder = null;
        private DataTable dataTable = null;
        private BindingSource bindingSource = null;
        private String selectQueryString = null;
        
        public frmGridVw()
        {
            InitializeComponent();
        }

        private void frmGridVw_Load(object sender, EventArgs e)
        {
            //   GridVw.Columns.Add("gvName" , "name");
            //showAllData();
            // txtgdvPhoneSearch.Focus();
            // GridVw.Enabled = false;
            Customer.DB.DbCon_call showDb = new Customer.DB.DbCon_call();
            try
            {
                showDb.con.Open();
                //da = new SqlDataAdapter("SELECT CustID as 'Customer ID', CustName as Name,CustPhoneNo as 'Phone No' , CustAddress as Address, CustBloodGroup as 'Blood Group', CustFatherName as 'Father''s Name', CustMotherName as 'Mother''s Name' FROM r_customer", showDb.con);

                selectQueryString = "SELECT CustID as 'Customer ID', CustName as Name,CustPhoneNo as 'Phone No' , CustAddress as Address, CustBloodGroup as 'Blood Group', CustFatherName as 'Father''s Name', CustMotherName as 'Mother''s Name' FROM r_customer";
                sqlDataAdapter = new SqlDataAdapter(selectQueryString, showDb.con);
                sqlCommandBuilder = new SqlCommandBuilder(sqlDataAdapter);

                //                ds = new DataSet();
                dataTable = new DataTable();
                sqlDataAdapter.Fill(dataTable);
                bindingSource = new BindingSource();
                bindingSource.DataSource = dataTable;
                GridVw.DataSource = bindingSource;
            }
            catch (Exception ex)
            {
                if (showDb.con.State.Equals("Open"))
                {
                   // showDb.con.Close();
                }
                System.Windows.Forms.MessageBox.Show(ex.Message);
            }
        }

        public void button1_Click(object sender, EventArgs e)
        {
            GridVw.Enabled = true;
            //  showAllData();
           // searchData();
        }

        //private void GridVw_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
        //{
        //    //string str;
        //    //str = GridVw.SelectedCells[0].Value.ToString();
        //    //textBox1.Text= str;
        //}

        public void showAllData()
        {
            Customer.DB.DbCon_call showDb = new Customer.DB.DbCon_call();
            try
            {
                showDb.con.Open();
                //da = new SqlDataAdapter("SELECT CustID as 'Customer ID', CustName as Name,CustPhoneNo as 'Phone No' , CustAddress as Address, CustBloodGroup as 'Blood Group', CustFatherName as 'Father''s Name', CustMotherName as 'Mother''s Name' FROM r_customer", showDb.con);

                selectQueryString = "SELECT CustID as 'Customer ID', CustName as Name,CustPhoneNo as 'Phone No' , CustAddress as Address, CustBloodGroup as 'Blood Group', CustFatherName as 'Father''s Name', CustMotherName as 'Mother''s Name' FROM r_customer";
                sqlDataAdapter = new SqlDataAdapter(selectQueryString, showDb.con);

                sqlCommandBuilder = new SqlCommandBuilder(sqlDataAdapter);
                
                //                ds = new DataSet();
                dataTable = new DataTable();
                sqlDataAdapter.Fill(dataTable);
                bindingSource = new BindingSource();
                bindingSource.DataSource = dataTable;
                GridVw.DataSource = bindingSource;
            }
            catch (Exception ex)
            {
                if (showDb.con.State.Equals("Open"))
                {
                    showDb.con.Close();
                }
                System.Windows.Forms.MessageBox.Show(ex.Message);
            }
        }

        public void searchData()
        {
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Customer.DB.DbCon_call showDb = new Customer.DB.DbCon_call();
            try
            {
                showDb.con.Open();
                sqlDataAdapter.Update(dataTable);
            }
            catch (Exception exceptionObj)
            {
                MessageBox.Show(exceptionObj.Message.ToString());
               // txtgdvPhoneSearch.Text = exceptionObj.Message;
            }

        }
    }
}