DropDownList 总是删除第一个值？

Question

i'm creating a recipe website for meals. I make an admin panel and i want to delete a meal which i added before. And there is a menu which includes number of the meal. For example there are 4 meals in pasta category and it shows Pasta(4) at mainpage. Me as an admin, if i would like to add a new meal to my website, it's working. I select a category and it's adding to that category. But for deleting, it's working wrong. It always delete the first value in DropDownList which is Meat Foods. Can you help me to find an answer?

Here is the code:

if (Page.IsPostBack == false)
{
    id = Request.QueryString["YemekId"];
    islem = Request.QueryString["islem"];

    SqlCommand komut2 = new SqlCommand("Select *from Kategoriler", baglan.baglanti());
    SqlDataReader oku2 = komut2.ExecuteReader();
    DropDownList1.DataTextField = "KategoriAd"; //DropDownList'e kategorilerin adlarını text biçiminde oldukları için bu şekilde çektik.
    DropDownList1.DataValueField = "KategoriId"; //DropDownList'e kategorilerin id nolarını value değerinde oldukları için bu şekilde çektik.
    DropDownList1.DataSource = oku2;
    DropDownList1.DataBind();

    SqlCommand komut = new SqlCommand("Select *from Yemek", baglan.baglanti());
    SqlDataReader oku = komut.ExecuteReader();
    DataList1.DataSource = oku;
    DataList1.DataBind();
}

//silme işlemi
if (islem == "sil")
{
    SqlCommand komutsilme = new SqlCommand("Delete from Yemek where YemekId=@s1", baglan.baglanti());
    komutsilme.Parameters.AddWithValue("@s1", id);
    komutsilme.ExecuteNonQuery();
    baglan.baglanti().Close();

    SqlCommand kategorisil = new SqlCommand("Update Kategoriler set KategoriAdet=KategoriAdet-1 where KategoriId=@k1", baglan.baglanti());
    kategorisil.Parameters.AddWithValue("@k1", DropDownList1.SelectedValue);
    kategorisil.ExecuteNonQuery();
    baglan.baglanti().Close();

    Response.Write("<script> alert('Yemek başarıyla silindi!')</script>");
}

Answer 1

you are passing a id as a string from your query string to the parameter

komutsilme.Parameters.AddWithValue("@s1", id);

I am assuming YemekId is an int in your database so try this

komutsilme.Parameters.AddWithValue("@s1", int.Parse(id));

AddWithValue will derive the type of the parameter of its value, so ensure that it's the correct type, in this case int not string.