Hey Alauddin,

Please refer below sample.

HTML

<asp:GridView ID="gvCustomers" runat="server" AutoGenerateColumns="false" OnRowDataBound="OnRowDataBound"
    AllowPaging="true" PageSize="2" DataKeyNames="CustomerId" OnPageIndexChanging="gvCustomers_PageIndexChanging"
    OnPageIndexChanged="gvCustomers_PageIndexChanged">
    <Columns>
        <asp:TemplateField>
            <HeaderTemplate>
                <asp:CheckBox ID="chkAll" runat="server" AutoPostBack="true" />
            </HeaderTemplate>
            <ItemTemplate>
                <asp:CheckBox runat="server" AutoPostBack="true" />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Name">
            <ItemTemplate>
                <asp:Label runat="server" Text='<%# Eval("Name") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Country">
            <ItemTemplate>
                <asp:Label ID="lblCountry" runat="server" Text='<%# Eval("Country") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>
<br />
<asp:Button ID="btnUpdate" runat="server" Text="Display" OnClick="Update" />
<asp:Label ID="lblMessage" runat="server" />
<asp:GridView runat="server" ID="gvCheckedCustomers" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="CustomerId" HeaderText="CustomerId" />
        <asp:BoundField DataField="Name" HeaderText="Name" />
        <asp:BoundField DataField="Country" HeaderText="Country" />
    </Columns>
</asp:GridView>

Namespaces

C#

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

VB.Net

Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.Linq

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        this.BindGrid();
    }
}

private void BindGrid()
{
    SqlCommand cmd = new SqlCommand("SELECT CustomerId, Name, Country FROM Customers");
    gvCustomers.DataSource = this.ExecuteQuery(cmd, "SELECT");
    gvCustomers.DataBind();
    if (ViewState["UpdatedRecord"] == null)
    {
        ViewState["UpdatedRecord"] = this.ExecuteQuery(cmd, "SELECT").Clone();
    }
}

private DataTable ExecuteQuery(SqlCommand cmd, string action)
{
    string conString = ConfigurationManager.ConnectionStrings["constring"].ConnectionString;
    using (SqlConnection con = new SqlConnection(conString))
    {
        cmd.Connection = con;
        switch (action)
        {
            case "SELECT":
                using (SqlDataAdapter sda = new SqlDataAdapter())
                {
                    sda.SelectCommand = cmd;
                    using (DataTable dt = new DataTable())
                    {
                        sda.Fill(dt);
                        return dt;
                    }
                }
        }
        return null;
    }
}
protected void Update(object sender, EventArgs e)
{
    DataTable dt = ViewState["UpdatedRecord"] as DataTable;
    string name = string.Empty;
    string country = string.Empty;
    if (dt != null)
    {
        for (int i = 0; i < gvCustomers.Rows.Count; i++)
        {
            GridViewRow row = gvCustomers.Rows[i];
            bool isChecked = row.Cells[0].Controls.OfType<CheckBox>().FirstOrDefault().Checked;
            if (isChecked)
            {
                name += row.Cells[1].Controls.OfType<Label>().FirstOrDefault().Text;
                country += row.Cells[2].Controls.OfType<Label>().FirstOrDefault().Text;
                int id = Convert.ToInt32(gvCustomers.DataKeys[row.RowIndex].Value);
                dt.Rows.Add(id, name, country);
            }
        }
    }
    gvCustomers.PageIndex = 0;
    this.BindGrid();
    ViewState["UpdatedRecord"] = null;
    gvCheckedCustomers.DataSource = dt;
    gvCheckedCustomers.DataBind();
    lblMessage.Text = "Count is : " + dt.Rows.Count.ToString();
}


protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        SqlCommand cmd = new SqlCommand("SELECT DISTINCT(Country) FROM CustomerTest11");
        string country = (e.Row.FindControl("lblCountry") as Label).Text;
    }
}

protected void gvCustomers_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    gvCustomers.PageIndex = e.NewPageIndex;
    if (ViewState["UpdatedRecord"] != null)
    {
        DataTable dtUpdated = ViewState["UpdatedRecord"] as DataTable;
        for (int i = 0; i < gvCustomers.Rows.Count; i++)
        {
            GridViewRow row = gvCustomers.Rows[i];
            bool isChecked = row.Cells[0].Controls.OfType<CheckBox>().FirstOrDefault().Checked;
            if (isChecked)
            {
                int id = Convert.ToInt32(gvCustomers.DataKeys[row.RowIndex].Value);
                DataRow dr = dtUpdated.Select("CustomerId=" + id).Length > 0 ? dtUpdated.Select("CustomerId=" + id)[0] : null;
                if (dr != null)
                {
                    dtUpdated.Rows.Remove(dr);
                }
                string name = row.Cells[1].Controls.OfType<Label>().FirstOrDefault().Text;
                string country = row.Cells[2].Controls.OfType<Label>().FirstOrDefault().Text;
                dtUpdated.Rows.Add(id, name, country);

                ViewState["UpdatedRecord"] = dtUpdated;
            }
        }
    }
    this.BindGrid();
}
protected void gvCustomers_PageIndexChanged(object sender, EventArgs e)
{
    if (ViewState["UpdatedRecord"] != null)
    {
        DataTable dtUpdated = ViewState["UpdatedRecord"] as DataTable;
        foreach (GridViewRow row in gvCustomers.Rows)
        {
            if (row.RowType == DataControlRowType.DataRow)
            {
                int id = Convert.ToInt32(gvCustomers.DataKeys[row.RowIndex].Value);
                DataRow dr = dtUpdated.Select("CustomerId=" + id).Length > 0 ? dtUpdated.Select("CustomerId=" + id)[0] : null;
                if (dr != null)
                {
                    row.Cells[0].Controls.OfType<CheckBox>().FirstOrDefault().Checked = true;
                    bool isChecked = row.Cells[0].Controls.OfType<CheckBox>().FirstOrDefault().Checked;
                    for (int i = 1; i < row.Cells.Count; i++)
                    {
                        row.Cells[i].Controls.OfType<Label>().FirstOrDefault().Visible = !isChecked;
                        if (row.Cells[i].Controls.OfType<Label>().ToList().Count > 0)
                        {
                            row.Cells[i].Controls.OfType<Label>().FirstOrDefault().Visible = isChecked;
                            row.Cells[i].Controls.OfType<Label>().FirstOrDefault().Text = dr["Name"].ToString();
                        }
                        if (row.Cells[i].Controls.OfType<Label>().ToList().Count > 0)
                        {
                            row.Cells[i].Controls.OfType<Label>().FirstOrDefault().Visible = isChecked;
                            row.Cells[i].Controls.OfType<Label>().FirstOrDefault().Text = dr["Name"].ToString();
                        }
                    }
                }
            }
        }
    }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Me.BindGrid()
    End If
End Sub

Private Sub BindGrid()
    Dim cmd As SqlCommand = New SqlCommand("SELECT CustomerId, Name, Country FROM Customers")
    gvCustomers.DataSource = Me.ExecuteQuery(cmd, "SELECT")
    gvCustomers.DataBind()

    If ViewState("UpdatedRecord") Is Nothing Then
        ViewState("UpdatedRecord") = Me.ExecuteQuery(cmd, "SELECT").Clone()
    End If
End Sub

Private Function ExecuteQuery(ByVal cmd As SqlCommand, ByVal action As String) As DataTable
    Dim conString As String = ConfigurationManager.ConnectionStrings("constring").ConnectionString

    Using con As SqlConnection = New SqlConnection(conString)
        cmd.Connection = con

        Select Case action
            Case "SELECT"

                Using sda As SqlDataAdapter = New SqlDataAdapter()
                    sda.SelectCommand = cmd

                    Using dt As DataTable = New DataTable()
                        sda.Fill(dt)
                        Return dt
                    End Using
                End Using
        End Select

        Return Nothing
    End Using
End Function

Protected Sub Update(ByVal sender As Object, ByVal e As EventArgs)
    Dim dt As DataTable = TryCast(ViewState("UpdatedRecord"), DataTable)
    Dim name As String = String.Empty
    Dim country As String = String.Empty

    If dt IsNot Nothing Then

        For i As Integer = 0 To gvCustomers.Rows.Count - 1
            Dim row As GridViewRow = gvCustomers.Rows(i)
            Dim isChecked As Boolean = row.Cells(0).Controls.OfType(Of CheckBox)().FirstOrDefault().Checked

            If isChecked Then
                name += row.Cells(1).Controls.OfType(Of Label)().FirstOrDefault().Text
                country += row.Cells(2).Controls.OfType(Of Label)().FirstOrDefault().Text
                Dim id As Integer = Convert.ToInt32(gvCustomers.DataKeys(row.RowIndex).Value)
                dt.Rows.Add(id, name, country)
            End If
        Next
    End If

    gvCustomers.PageIndex = 0
    Me.BindGrid()
    ViewState("UpdatedRecord") = Nothing
    gvCheckedCustomers.DataSource = dt
    gvCheckedCustomers.DataBind()
    lblMessage.Text = "Count is : " & dt.Rows.Count.ToString()
End Sub

Protected Sub OnRowDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
    If e.Row.RowType = DataControlRowType.DataRow Then
        Dim cmd As SqlCommand = New SqlCommand("SELECT DISTINCT(Country) FROM CustomerTest11")
        Dim country As String = (TryCast(e.Row.FindControl("lblCountry"), Label)).Text
    End If
End Sub

Protected Sub gvCustomers_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs)
    gvCustomers.PageIndex = e.NewPageIndex

    If ViewState("UpdatedRecord") IsNot Nothing Then
        Dim dtUpdated As DataTable = TryCast(ViewState("UpdatedRecord"), DataTable)

        For i As Integer = 0 To gvCustomers.Rows.Count - 1
            Dim row As GridViewRow = gvCustomers.Rows(i)
            Dim isChecked As Boolean = row.Cells(0).Controls.OfType(Of CheckBox)().FirstOrDefault().Checked

            If isChecked Then
                Dim id As Integer = Convert.ToInt32(gvCustomers.DataKeys(row.RowIndex).Value)
                Dim dr As DataRow = If(dtUpdated.[Select]("CustomerId=" & id).Length > 0, dtUpdated.[Select]("CustomerId=" & id)(0), Nothing)

                If dr IsNot Nothing Then
                    dtUpdated.Rows.Remove(dr)
                End If

                Dim name As String = row.Cells(1).Controls.OfType(Of Label)().FirstOrDefault().Text
                Dim country As String = row.Cells(2).Controls.OfType(Of Label)().FirstOrDefault().Text
                dtUpdated.Rows.Add(id, name, country)
                ViewState("UpdatedRecord") = dtUpdated
            End If
        Next
    End If

    Me.BindGrid()
End Sub

Protected Sub gvCustomers_PageIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
    If ViewState("UpdatedRecord") IsNot Nothing Then
        Dim dtUpdated As DataTable = TryCast(ViewState("UpdatedRecord"), DataTable)

        For Each row As GridViewRow In gvCustomers.Rows

            If row.RowType = DataControlRowType.DataRow Then
                Dim id As Integer = Convert.ToInt32(gvCustomers.DataKeys(row.RowIndex).Value)
                Dim dr As DataRow = If(dtUpdated.[Select]("CustomerId=" & id).Length > 0, dtUpdated.[Select]("CustomerId=" & id)(0), Nothing)

                If dr IsNot Nothing Then
                    row.Cells(0).Controls.OfType(Of CheckBox)().FirstOrDefault().Checked = True
                    Dim isChecked As Boolean = row.Cells(0).Controls.OfType(Of CheckBox)().FirstOrDefault().Checked

                    For i As Integer = 1 To row.Cells.Count - 1
                        row.Cells(i).Controls.OfType(Of Label)().FirstOrDefault().Visible = Not isChecked

                        If row.Cells(i).Controls.OfType(Of Label)().ToList().Count > 0 Then
                            row.Cells(i).Controls.OfType(Of Label)().FirstOrDefault().Visible = isChecked
                            row.Cells(i).Controls.OfType(Of Label)().FirstOrDefault().Text = dr("Name").ToString()
                        End If

                        If row.Cells(i).Controls.OfType(Of Label)().ToList().Count > 0 Then
                            row.Cells(i).Controls.OfType(Of Label)().FirstOrDefault().Visible = isChecked
                            row.Cells(i).Controls.OfType(Of Label)().FirstOrDefault().Text = dr("Name").ToString()
                        End If
                    Next
                End If
            End If
        Next
    End If
End Sub

Screenshot