Kay Here, I Have This Code That Keeps Generation This Error "Throw New Notimplementedexception();" ...Please Help

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.Configuration;
using System.Data;

public partial class Default2 : System.Web.UI.Page
{

    public string strconnString { get; set; }private string strConnString = ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DataBind();

            string strQuery = "select Reader_name, book_name,book_author,borrow_date,expected return_date" + "from readers Query";
            SqlCommand cmd = new SqlCommand(strQuery);
            GridView1.DataSource = GetData(cmd);
            GridView1.DataBind();
        }
    }
    protected void EditReader(object sender, GridViewEditEventArgs e)
    {

        GridView1.EditIndex = e.NewEditIndex;

        DataBind();

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


    protected void UpdateReader(object sender, GridViewUpdateReaderEventArgs e)
    {
        string Readername = ((TextBox)GridView1.Rows[e.RowIndex].FindControl("txtReadername")).Text;
        string Bookname = ((TextBox)GridView1.Rows[e.RowIndex].FindControl("txtbookname")).Text;
        string Bookauthor = ((TextBox)GridView1.Rows[e.RowIndex].FindControl("txtBokkauthor")).Text;
        string BorrowDate = ((TextBox)GridView1.Rows[e.RowIndex].FindControl("txtBorrowdate")).Text;
        string ExpectedreturnDate = ((TextBox)GridView1.Rows[e.RowIndex].FindControl("txtexpectedreturndate")).Text;
        SqlConnection con = new SqlConnection(strconnString);
        SqlCommand cmd = new SqlCommand();

        cmd.CommandType = CommandType.Text;
        cmd.CommandText = "update Reader name=@Reader name," + "Book name=@Book name," + "Book author=@Book author, " + " Borrow date=@Borrow date ," + " expected return date=@expected return date where Reader name=@reader name;" +
            "select Reader name,Book name,Book author,Borrow date,expected return date from Query table";

        cmd.Parameters.Add("@Readername", SqlDbType.VarChar).Value = Readername;
        cmd.Parameters.Add("@Bookname", SqlDbType.VarChar).Value = Bookname;
        cmd.Parameters.Add("@Bookauthor", SqlDbType.VarChar).Value = Bookauthor;
        cmd.Parameters.Add("@BorrowDate", SqlDbType.VarChar).Value = BorrowDate;
        cmd.Parameters.Add("@ExpectedreturnDate", SqlDbType.VarChar).Value = ExpectedreturnDate;

        GridView1.EditIndex = -1;

        GridView1.DataSource = GetData(cmd);

        GridView1.DataBind();


   
    protected void DeleteReader(object sender, EventArgs e)
    {
        LinkButton lnkRemove = (LinkButton)sender;
        SqlConnection con = new SqlConnection(strConnString);
        SqlCommand cmd = new SqlCommand();
        cmd.CommandType = CommandType.Text;
        cmd.CommandText = "delete from readers Query  where " + "Readerame=@Readername;" + "select Reader name,Book name,Book author,Borrow date,expected return date from reader Query";
        cmd.Parameters.Add("@Readername", SqlDbType.VarChar).Value = lnkRemove.CommandArgument;
        GridView1.DataSource = GetData(cmd);
        GridView1.DataBind();


  
    }
}