Thread: Problem in DropDownList's SelectedIndexChanged Event

  1. #1
    Registered User Aga^^'s Avatar
    Join Date
    Aug 2008

    Question Problem in DropDownList's SelectedIndexChanged Event

    hi guys,
    i am working on a library automation system in ASP.NET with C#. I think this part of the forum is suitable.
    When i come to my problem
    in admin panel i designed a "Book Addition" page . In this part admin choose category and subcategory to add the book. The category names will be listed on Page_Load, admin chooses a category name and the subcategories which is related to the choosen category will listed on ddlSubcategory.

    here is my code
    int i;
    protected void ddlCat_SelectedIndexChanged(object sender, EventArgs e)
            SqlConnection connect = dbConnection.GetConnection();
            SqlCommand cmd2 = new SqlCommand("select c_id from categories where c_name=@catname", connect);
            cmd2.Parameters.AddWithValue("@catname", ddlCat.SelectedValue.ToString());
            //cmd2.Parameters.AddWithValue("@catname", ddlCategory.SelectedItem.Value);
            SqlDataReader rdr2 = cmd2.ExecuteReader();
            while (rdr2.Read())
                i = Int32.Parse(rdr2.GetValue(0).ToString());
            SqlCommand command2 = new SqlCommand("select s_name,s_id from subcategories where c_id=@i", connect);
            command2.Parameters.AddWithValue("@i", i);
            SqlDataAdapter da = new SqlDataAdapter(command2);
            DataTable dt = new DataTable();
            ddlScat.DataSource = dt;
            ddlScat.DataTextField = "s_name";
            ddlScat.DataValueField = "s_id";
    there is no warning or error. And Page_load part is working correctly but when i clicked ddlCat ( drop down list of Categories ) the ddlScat ' s( drop down list of subcategories ) items do not change.

    i am waiting your answers..
    Last edited by Aga^^; 07-17-2009 at 04:54 AM. Reason: i is defined before

  2. #2
    Confused Magos's Avatar
    Join Date
    Sep 2001
    Have you set the "AutoPostback" property on the dropdownlist to True?

    Give a man a fish and you feed him for a day.
    Teach a man to fish and you feed him for a lifetime.

  3. #3
    Registered User Aga^^'s Avatar
    Join Date
    Aug 2008
    yeah that's it thanks a lot Magos

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