Insert multiple data in database from gridview using Select All button

<asp:GridView ID="grdSelectEmp" runat="server" AllowPaging="false"
                                            AutoGenerateColumns="False" CellPadding="4" EmptyDataText="No Record Exists"
                                            ForeColor="#333333" GridLines="Both" Height="450px" Width="100%"
                                            onrowcommand="grdSelectEmp_RowCommand">
                                            <AlternatingRowStyle BackColor="White" HorizontalAlign="Left" />
                                            <Columns>
                                                <asp:TemplateField HeaderStyle-HorizontalAlign="Left" HeaderText="Employee ID" ItemStyle-HorizontalAlign="Left">
                                                    <ItemTemplate>
                                                        <asp:Label ID="lblEmpId" runat="server" ForeColor="#333333" Text='<%# Eval("EmpCode")%>'></asp:Label>
                                                    </ItemTemplate>
                                                </asp:TemplateField>
                                                <asp:TemplateField HeaderStyle-HorizontalAlign="Left" HeaderText="Employee Name" ItemStyle-HorizontalAlign="Left">
                                                    <ItemTemplate>
                                                        <asp:Label ID="lblEmpName" runat="server" ForeColor="#333333" Text='<%# Eval("EmapName")%>'></asp:Label>
                                                    </ItemTemplate>
                                                </asp:TemplateField>
                                                <asp:TemplateField HeaderStyle-HorizontalAlign="Left" HeaderText="Designation" ItemStyle-HorizontalAlign="Left">
                                                    <ItemTemplate>
                                                        <asp:Label ID="lblDesignation" runat="server" ForeColor="#333333" Text='<%# Eval("DesignationName")%>'></asp:Label>
                                                    </ItemTemplate>
                                                </asp:TemplateField>
                                                <asp:TemplateField HeaderStyle-HorizontalAlign="Left" ItemStyle-HorizontalAlign="Left">
                                                    <HeaderTemplate>
                                                        <asp:Button ID="btnSelectAll" runat="server" CommandName="SelectAll_Clicked" Text="Select All" Width="80px" />
                                                    </HeaderTemplate>
                                                    <ItemTemplate>
                                                        <asp:CheckBox ID="chkEmp" runat="server" AutoPostBack="true" />
                                                    </ItemTemplate>
                                                </asp:TemplateField>
                                            </Columns>
                                            <EditRowStyle />
                                            <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
                                            <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White"
                                                HorizontalAlign="Left" />
                                            <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />
                                            <RowStyle BackColor="#EFF3FB" HorizontalAlign="Left" />
                                        </asp:GridView>

.cs Code

 protected void btnSendNotification_Click(object sender, EventArgs e)
        {
            try
            {
                lblError.Visible = false;
                foreach (GridViewRow grdRow in grdSelectEmp.Rows)
                {
                    if (((CheckBox)grdRow.FindControl("chkEmp")).Checked == true)
                    {
                        SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConStr"].ToString());
                        conn.Open();
                        SqlCommand cmd = new SqlCommand("proc_MeetingNotify", conn);
                        cmd.Parameters.AddWithValue("@Title", txtTitle.Text.Trim());
                        cmd.Parameters.AddWithValue("@MeetingDate", txtDate.Text.Trim());
                        cmd.Parameters.AddWithValue("@Location", txtLocation.Text.Trim());
                        cmd.Parameters.AddWithValue("@MeetingTime", txtTime.Text.Trim());
                        cmd.Parameters.AddWithValue("@EmpID", ((Label)grdRow.FindControl("lblEmpId")).Text.Trim());
                        cmd.Parameters.AddWithValue("@BranchID", ddlBranch.SelectedItem.Value);
                        cmd.Parameters.AddWithValue("@DepartmentID", ddlDepartment.SelectedItem.Value);
                        cmd.Parameters.AddWithValue("@EnteredBy", ViewState["user"].ToString());
                        cmd.CommandType = CommandType.StoredProcedure;
                        cmd.ExecuteNonQuery();
                        conn.Close();
                        conn.Dispose();                      
                    }

                }
                lblError.Visible = true;
                lblError.Text = "Notofication Has Send";
                Insert_Notification();
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }