How to capture logout time

I need to capture the logout time and login time. I can capture the login time already but I cannot capture the logout time. I would appreciate all the help that you had given me. Thank you.
This is the coding in the logout button:

Code:

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protected void logoutButton_Click(object sender, EventArgs e)
        {
            SqlCommand cmd = new SqlCommand("SELECT TOP 1 LogId FROM LoggedInUsers where MemberID = @MemberID ORDER BY LogId DESC");
            cmd.Parameters.AddWithValue("@MemberID", Session["MemberID"]);
            Session.Abandon();
        }

I also need to do in global.asax. And this is the coding:

protected void Session_End(object sender, EventArgs e)
        {
            if (Session["MemberId"] != null)
            {
                UpdateLoggedInUsersLogoutTime(Convert.ToInt32(Session["MemberId"].ToString()));
            }
            //string emailaddress = (string)Session["emailaddress"];



        }protected Boolean UpdateLoggedInUsersLogoutTime(int MemberID)
       
        {
            SqlConnection connection = null;
            SqlCommand command = null;
            Boolean successFlag = false;


            try
            {


                string connectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
                connection = new SqlConnection(connectionString);
                connection.Open();


                //retrieve the logid
                string connectionString1 = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
                connection = new SqlConnection(connectionString1);
                connection.Open();
                //prepare sql statements
                //string sql = "SELECT * from LoggedInUsers where emailaddress='" + emailaddress + "' And Password='" + password + "'";
                //Response.Write(sql);
                //command = new SqlCommand(sql, connection);
                SqlDataAdapter da = new SqlDataAdapter(command);
                DataTable dt = new DataTable();
                da.Fill(dt);
                if (dt.Rows.Count > 0)
                {
                   
                /* add value to Session */
                Session["LogId"] = dt.Rows[0]["LogId"].ToString();
                   
                SqlCommand cmd = new SqlCommand("SELECT TOP 1 LogId FROM LoggedInUsers where MemberID = @MemberID ORDER BY LogId DESC");
                cmd.Parameters.AddWithValue("@MemberID", MemberID);
                //pass the session
                int logid = (int)Session["MemberId"];


                DateTime dateTime = DateTime.Now;
                string s = dateTime.ToString(); 
               
                //update record based on logid
                SqlCommand cmd1 = new SqlCommand("UPDATE LoggedInUsers set LogoutTime = '" + s + "' Where MemberID = @MemberID");
               
                //prepare sql statements
                string sql1 = "UPDATE  LoggedInUsers set LogoutTime= '" + s + "' where emailaddress=@EmailAddress";
                //Response.Write(sql + "<br />");


                //command = new SqlCommand(cmd1, connection);
                //command.Parameters.Clear();
                command.Parameters.AddWithValue("@LogoutTime", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));
                command.Parameters.AddWithValue("MemberID", MemberID);


                int rowCount = command.ExecuteNonQuery();
                //if (rowCount != 0)
                if (rowCount == 1)
                {
                    successFlag = true;
                    //Response.Write("Operation success.<br/>");
                }
                else
                {
                    //Response.Write("Operation failed<br/>");
                }
              }
            }


                catch (Exception ex)
                {
                //Response.Write("Error:" + ex.Message);
                }
                //cleanup object
                finally
                {
                if (connection != null)
                    connection.Close();
                }


                return successFlag;
            }
        }
       
      }

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Add log out function call in btn_Logout and not from Global.asax