how to select and read data in dropdownlist?

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hello.
I intend to bind my dropdownlist to sqlserver and read the items(CityName)that i have them in DB(Table City)and then list and fill them into the dropdownlist.
for this matter i have written the code below in Page_load that whenever i start to debug all city items to be seen in dropdownlist:

C#

protected void Page_Load(object sender, EventArgs e)
       {
           SqlConnection conn = new SqlConnection();
           SqlCommand cmd = new SqlCommand();
           conn.ConnectionString = ConfigurationManager.ConnectionStrings["PersonTest"].ConnectionString;

           conn.Open();
           cmd.CommandText = "SELECT CityName FROM City";
           cmd.Parameters.Add("@CityName", SqlDbType.NVarChar).Value = DropCity.AppendDataBoundItems;
           cmd.ExecuteReader();
           conn.Close();
       }

but in line (cmd.ExecuteReader();) this error occurs:

InvalidOperationException was unhandled by user code.
ExecuteReader: Connection property has not been initialized

meanwhile i know that i can use ASP.net DataBinding(by wizard)ability, but i want to do it with myself . and also i don't know which one is better to be used in forms? which one do you suggest to use?

Posted 21-Jul-12 20:29pm

mohammad ehsan

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Comments

JakirBB 22-Jul-12 2:54am

Did you make any relation between cmd and conn in your code?

JakirBB 22-Jul-12 3:00am

Which connection will be used by cmd. Why have you add parameters though in SQL there is no use of?

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Mohamed Mitwalli · Answer 1 · 2012-07-21T21:25:00

Hi ,
you can use this for bind data to your dropdownlist

C#

if (!IsPostBack)
    {
        using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["PersonTest"].ConnectionString))
        {
            conn.Open();
            using (SqlCommand cmd = new SqlCommand("SELECT CityName , id FROM City", conn))
            {
                DataTable dt = new DataTable();
                SqlDataAdapter adpt = new SqlDataAdapter(cmd);
                adpt.Fill(dt);
                DropCity.DataTextField = "CityName";
                DropCity.DataValueField = "id";
            }
        } 
    }

and for select the value of dropdownlist you can use SelectedValue
Best Regards
M.Mitwalli