Question

I have a table in my sql database, that comtains data.
In this table, I have the id (int), and two two column names (each nvarchar(50) ).
Now. Say. Using C# in codebehind, I want to place one of the “nvarchar” in a string.
I wish to use the id from my browsers url, to choose the data with.

Lets say, my url is “http://localhost:49530/Forum/Thread.aspx?id=4”
In my table, I have ThreadID, Topic and Message.
So it needs to write the data from “Topic”, that has ThreadID=4, into a predefined variable.

I wish to do it in page_load in code behind. And finally show that data in a label on the aspx page.

I am totally blank. (as well as what to google for. Have googled the whole day on this).

I have cooked some code now, using the example given to me. Something is wrong.

SqlConnection conn_Kategori = new SqlConnection(WebConfigurationManager.ConnectionStrings["Computer_Klubben_CommunitySiteConnectionString"].ConnectionString);
int TraadVaelger = int.Parse(Request.QueryString["id"]);
string OutputToLabel;

    using (conn_Kategori)
    {
        conn_Kategori.Open();
        SqlCommand OverfoerTraadNavnet = new SqlCommand("SELECT KatNavn FROM KategoriTabel WERE Katnavn = @KatNavn", conn_Kategori);
        OverfoerTraadNavnet.CommandType = CommandType.Text;
        OverfoerTraadNavnet.Parameters.AddWithValue("@KatNavn", TraadVaelger);
        OverfoerTraadNavnet.ExecuteReader();
        OutputToLabel = OverfoerTraadNavnet.ExecuteReader().ToString();
        Stien.Text = OutputToLabel;
        conn_Kategori.Close();
    }

Answer 1

string OutputToLabel = string.Empty;

if(!string.IsNullOrEmpty(Request.QueryString["id"]))
{
    int ThreadID = 0;
    int.TryParse(Request.QueryString["id"], out ThreadID);
    if(ThreadID > 0)
    {
        string Sql = "SELECT Topic FROM <tablename> WHERE ThreadID = @ThreadID;";
        using (SqlConnection conn = new SqlConnection(connString))
        {
            SqlCommand cmd = new SqlCommand(Sql, conn);
            cmd.Parameters.Add("@ThreadID", ThreadID);
            try
            {
                conn.Open();
                OutputToLabel = cmd.ExecuteScalar().ToString();
            }
            catch (Exception ex)
            {
                Response.Write(ex.Message);
            }
        }
    }
}