Hi satabeach,

Refer below sample.

For insert refer below links -

Insert (Save) data in Microsoft Access database using C# in ASP.Net

HTML

<asp:GridView ID="gvCustomers" runat="server">
</asp:GridView>

Namespaces

C#

using System.Data.SqlClient;
using System.Data;
using System.Configuration;

VB.Net

Imports System.Data
Imports System.Data.SqlClient

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = GetData();
        dt.Columns.Add("Sequence", typeof(int));
        int value = 1;
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            if (i % 3 > 0 || i == 0)
            {
                dt.Rows[i]["Sequence"] = value;
            }
            else
            {
                value++;
                dt.Rows[i]["Sequence"] = value;
            }
        }

        gvCustomers.DataSource = dt;
        gvCustomers.DataBind();
    }
}

private DataTable GetData()
{
    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["constr"].ConnectionString);
    SqlCommand cmd = new SqlCommand("SELECT TOP 6 CustomerID,ContactName FROM Customers", con);
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    DataTable dt = new DataTable();
    da.Fill(dt);

    return dt;
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As DataTable = GetData()
        dt.Columns.Add("Sequence", GetType(Integer))
        Dim value As Integer = 1
        For i As Integer = 0 To dt.Rows.Count - 1
            If i Mod 3 > 0 OrElse i = 0 Then
                dt.Rows(i)("Sequence") = value
            Else
                value += 1
                dt.Rows(i)("Sequence") = value
            End If
        Next
        gvCustomers.DataSource = dt
        gvCustomers.DataBind()
    End If
End Sub

Private Function GetData() As DataTable
    Dim con As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("constr").ConnectionString)
    Dim cmd As SqlCommand = New SqlCommand("SELECT TOP 6 CustomerID,ContactName FROM Customers", con)
    Dim da As SqlDataAdapter = New SqlDataAdapter(cmd)
    Dim dt As DataTable = New DataTable()
    da.Fill(dt)
    Return dt
End Function

Screenshot