How do i access checkbox checkchanged event in gridview?

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

private void LoadData()
{
  string constr = @"Server=.\SQLEXPRESS;Database=TestDB;uid=waqas;pwd=sql;";
  string query = @"SELECT CategoryID, CategoryName, Approved FROM Categories";

  SqlDataAdapter da = new SqlDataAdapter(query, constr);
  DataTable table = new DataTable();
  da.Fill(table);

  GridView1.DataSource = table;
  GridView1.DataBind();
}

public void chkStatus_OnCheckedChanged(object sender, EventArgs e)
{
    CheckBox chkStatus = (CheckBox)sender;
    GridViewRow row = (GridViewRow)chkStatus.NamingContainer;

    
    string cid = row.Cells[1].Text;
    bool status = chkStatus.Checked;

    
    string constr = @"Server=.\SQLEXPRESS;Database=TestDB;uid=waqas;pwd=sql;";
    string query = "UPDATE Categories SET Approved = @Approved WHERE CategoryID = @CategoryID";
        
    SqlConnection con = new SqlConnection(constr);
    SqlCommand com = new SqlCommand(query, con);

    
    com.Parameters.Add("@Approved", SqlDbType.Bit).Value = status;
    com.Parameters.Add("@CategoryID", SqlDbType.Int).Value = cid;

    
    con.Open();
    com.ExecuteNonQuery();
    con.Close();

    
    LoadData();
}

 the code for aspx is below

    BackColor="White" BorderColor="#336699" BorderStyle="Solid" BorderWidth="1px"  
    CellPadding="0" CellSpacing="0" DataKeyNames="CategoryID" Font-Size="10"
    Font-Names="Arial" GridLines="Vertical" Width="40%">
            
                        
               
                   
                                                    AutoPostBack="true" OnCheckedChanged="chkStatus_OnCheckedChanged"
                            Checked='<%# Convert.ToBoolean(Eval("Approved")) %>'
                            Text='<%# Eval("Approved").ToString().Equals("True") ? " Approved " : " Not Approved " %>' />
                                       
               
                
                                   
               
           
         

 Hope this will help you