无法从C＃中的列表中检索数据

Question

I'm designing a WinForms desktop application using C#.Net and MSSQL server. In the following class I read read the data from a stored procedure using sqlDataReader and I insert it in a List<> .

Later I want to show the list values in textboxes . My problem is that nothing is shown in the texboxes when I retrieve data from the list.

My stored procedure:

create proc spDispMaterialPrice
@materialName nvarchar(100)
as
begin 
select unitPrice,carbohydrate,protein,fat,humidity,minerals from materialPrice where 
materialName = @materialName
end 

Class:

    //display data retrived according to material combobox to user when form loads
    public List<string> displayMaterial()
    {
        List<string> materialList = new List<string>();
        string conString = ConfigurationManager.ConnectionStrings["secaloFormulaCS"].ToString();
        using (SqlConnection sqlCon = new SqlConnection(conString))
        using (SqlCommand sqlCmd = new SqlCommand("spDispMaterialPrice", sqlCon))
        {
            sqlCmd.CommandType = CommandType.StoredProcedure;
            sqlCon.Open();
            sqlCmd.Parameters.AddWithValue("materialName", MaterialName);                
            SqlDataReader sqlDr = sqlCmd.ExecuteReader();
            while (sqlDr.Read())
            {
                materialList[0] = sqlDr["unitPrice"].ToString();
                materialList[1] = sqlDr["carbohydrate"].ToString();
                materialList[2] = sqlDr["protein"].ToString();
                materialList[3] = sqlDr["fat"].ToString();
                materialList[4] = sqlDr["humidity"].ToString();
                materialList[5] = sqlDr["minerals"].ToString();
            }
            sqlCon.Close();
            sqlCon.Dispose();
        }
       return materialList;
    }
}

}

winform :

        private void AppForm_Load(object sender, EventArgs e)
        {
        this.materialPriceTableAdapter.Fill(this.secaloFormulaDataSet.materialPrice );
        //panel1.Hide();

        Classes.Prices prices = new Classes.Prices(comboBox1.SelectedItem.ToString());
        List<string> items = prices.displayMaterial();
        textBox3.Text = items[0];

Answer 1

You are using a List as if it is an array. Without changing to much of your code with the following change your code might work if there is one record selected from your table, otherwise it shows the last record that matches the materialname.

public string[] displayMaterial()
{
    var materialList = new string[6];

and in your AppForm_Load

string[] items = prices.displayMaterial();

Read the Commonly Used Collection Types from MSDN Development Fundamentals