.Net BackEnd Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;

namespace NET_Mockup
{
    public partial class Module_Details : System.Web.UI.Page
    {
        string connstring = @"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\crxss\source\repos\NET Mockup\NET Mockup\App_Data\metrodb.mdf;Integrated Security=True";
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                Populategride();
            }
        }
        void Populategride()
        {
            DataTable dtbl = new DataTable();
            using (SqlConnection sqcon = new SqlConnection(connstring))
            {
                sqcon.Open();
                SqlDataAdapter sqda = new SqlDataAdapter("Select * FROM module", sqcon);
                sqda.Fill(dtbl);
            }
            if (dtbl.Rows.Count > 0)
            {
                GridView1.DataSource = dtbl;
                GridView1.DataBind();
            }
            else
            {
                dtbl.Rows.Add(dtbl.NewRow());
                GridView1.DataSource = dtbl;
                GridView1.DataBind();
                GridView1.Rows[0].Cells.Clear();
                GridView1.Rows[0].Cells.Add(new TableCell());
                GridView1.Rows[0].Cells[0].ColumnSpan = dtbl.Columns.Count;
                GridView1.Rows[0].Cells[0].Text = "No Data Found!";
                GridView1.Rows[0].Cells[0].HorizontalAlign = HorizontalAlign.Center;
            }
        }

        protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            try
            {
                if (e.CommandName.Equals("AddNew"))
                {
                    using (SqlConnection sqcon = new SqlConnection(connstring))
                    {
                        sqcon.Open();
                        string query = "Insert into module(m_ID,m_name,learning_hours,lecturer) values(@m_ID,@m_name,@learning_hours,@lecturer)";
                        SqlCommand sqcom = new SqlCommand(query, sqcon);
                        sqcom.Parameters.AddWithValue("@m_ID", (GridView1.FooterRow.FindControl("text_m_ID_footer") as TextBox).Text.Trim());
                        sqcom.Parameters.AddWithValue("@m_name", (GridView1.FooterRow.FindControl("text_m_name_footer") as TextBox).Text.Trim());
                        sqcom.Parameters.AddWithValue("@learning_hours", (GridView1.FooterRow.FindControl("text_learning_hours_footer") as TextBox).Text.Trim());
                        sqcom.Parameters.AddWithValue("@lecturer", (GridView1.FooterRow.FindControl("text_lecturer_footer") as TextBox).Text.Trim());
                        sqcom.ExecuteNonQuery();
                        Populategride();
                        success.Text = "NEW RECORD INSERTED SUCCESSFULLY :-)";
                        error.Text = "";
                    }
                }
            }
            catch (Exception ex)
            {
                success.Text = "";
                error.Text = ex.Message;
            }

        }

        protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
        {
            try
            {
                using (SqlConnection sqcon = new SqlConnection(connstring))
                {
                    sqcon.Open();
                    string query = "update module set m_name=@m_name, learning_hours=@learning_hours, lecturer=@lecturer where m_ID=@m_ID";
                    SqlCommand sqcom = new SqlCommand(query, sqcon);
                    sqcom.Parameters.AddWithValue("@m_ID", (GridView1.Rows[e.RowIndex].FindControl("m_ID") as TextBox).Text.Trim());
                    sqcom.Parameters.AddWithValue("@m_name", (GridView1.Rows[e.RowIndex].FindControl("m_name") as TextBox).Text.Trim());
                    sqcom.Parameters.AddWithValue("@learning_hours", (GridView1.Rows[e.RowIndex].FindControl("learning_hours") as TextBox).Text.Trim());
                    sqcom.Parameters.AddWithValue("@lecturer", (GridView1.Rows[e.RowIndex].FindControl("lecturer") as TextBox).Text.Trim());

                    sqcom.ExecuteNonQuery();
                    Populategride();
                    success.Text = "NEW RECORD UPDATED :-)";
                    error.Text = "";
                }

            }
            catch (Exception ex)
            {
                success.Text = "";
                error.Text = ex.Message;
            }
        }

        protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
        {
            try
            {
                using (SqlConnection sqcon = new SqlConnection(connstring))
                {
                    sqcon.Open();
                    string query = "Delete from module where m_ID=@m_ID";
                    SqlCommand sqcom = new SqlCommand(query, sqcon);
                    sqcom.Parameters.AddWithValue("@m_ID", Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value.ToString()));
                    sqcom.ExecuteNonQuery();
                    Populategride();
                    success.Text = "<h3> DELETED SUCCESSFULLY :-( </h3>";
                    error.Text = "";
                }
            }
            catch (Exception ex)
            {
                success.Text = "";
                error.Text = ex.Message;
            }
        }

        protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
        {
            GridView1.EditIndex = -1;
            Populategride();
        }

        protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
        {
            GridView1.EditIndex = e.NewEditIndex;
            Populategride();
        }

        protected void Button1_Click(object sender, EventArgs e)
        {

        }
    }
}