data cannot update in database but update in datagridview c# windows application

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C#

Hi every one,

am developing windows application using c#.net, here i need to update and delete in datagridview, actually i done the above one that is which is updated and deleted in my side.
but the thing is the data cannot update in database but update in datagridview the same way has also deleting option, so please find out my code below where i did mistake why am not updating in database. please give me a solution.

thanks in advance...

my entire code is:

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


namespace tarriff_design_page
{
    public partial class testing : Form
    {
        
        // string s = @"Data Source=.\SQLEXPRESS;Initial Catalog=tarrif;User ID=sa;Password=sa";

        

        private SqlDataAdapter da;
        private SqlConnection conn;
        BindingSource bsource = new BindingSource();
        DataSet ds = null;
        string sql;


        public testing()
        {
            InitializeComponent();
          
            LoadData();
            
        }
        public static String hh
        {
            get
            {
                
            }
        }

       

        private void btnupdate_Click(object sender, EventArgs e)
        {
           
            try
{
DialogResult result = MessageBox.Show("Are you sure you want to proceed Updation ?", "Update Confirmation", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
if (result == DialogResult.Yes)
{
SqlConnection CN = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=tarrif;User ID=sa;Password=sa");
CN.Open();

string query = "Select * from test";

SqlDataAdapter dAdapter = new SqlDataAdapter(query, CN);

SqlCommandBuilder cBuilder = new SqlCommandBuilder(dAdapter);

DataTable dTable = new DataTable();

dAdapter.Fill(dTable);

DataGridView DGview = new DataGridView();

BindingSource bSource = new BindingSource();

DGview.DataSource = bSource;

dAdapter.Update(dTable);

CN.Close();

}
else
{

}

}
catch (Exception exceptionObj)
{
MessageBox.Show(exceptionObj.Message.ToString());
}

        }

        private void btndelete_Click(object sender, EventArgs e)
        {
            try
{
DialogResult result = MessageBox.Show("Are you sure you want to delete this row?", "Delete confirmation", MessageBoxButtons.YesNo, MessageBoxIcon.Question);

if (result == DialogResult.Yes)
{
foreach (DataGridViewRow dr in dataGridView1.SelectedRows)
{
if (dataGridView1.Rows.Count > 1)
dataGridView1.Rows.Remove(dr);
}
}
                }
catch (Exception exceptionObj)
{
MessageBox.Show(exceptionObj.Message.ToString());
}
        }



        public void LoadData()
        {
            string connectionString = @"Data Source=.\SQLEXPRESS;Initial Catalog=tarrif;User ID=sa;Password=sa";
            conn = new SqlConnection(connectionString);
            sql = "select * from test";
            da = new SqlDataAdapter(sql, conn);
            conn.Open();
            ds = new DataSet();
            SqlCommandBuilder commandBuilder = new SqlCommandBuilder(da);
            da.Fill(ds, "test");
            bsource.DataSource = ds.Tables["test"];
            dataGridView1.DataSource=bsource;
        }

        private void testing_Load(object sender, EventArgs e)
        {
            LoadData();
        }
    }
}