How do I use datavaluefield value as the parameter value in following query

See more:

Binding

I bind to dropdownlist, and am trying to use the datavalue as the parameter in my following query to bind to gridview. any help would be appreciated. Code below.

What I have tried:

public partial class ConsolidatedReport : System.Web.UI.Page
   {
       protected void Page_Load(object sender, EventArgs e)
       {
           BindCustomersDDL();
       }

       private void BindCustomersDDL()
       {
           DataTable dt = new DataTable();
           using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["AMTConnectionString"].ConnectionString))
           {
               con.Open();
               SqlCommand cmd = new SqlCommand("Select * from dbo.customer order by 2", con);
               SqlDataAdapter da = new SqlDataAdapter(cmd);
               da.Fill(dt);
           }
           ddlCustomer.DataSource = dt;
           ddlCustomer.DataTextField = "cname";//Which you want to display inthe dropdownlist
           ddlCustomer.DataValueField = "customerid";
           ddlCustomer.DataBind();


       }

       protected void btnExecute_Click(object sender, EventArgs e)
       {
           BindBacteriaGrid();

       }

       private void BindBacteriaGrid()
       {
           DataTable dt = new DataTable();
           try
           {
               SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["AMTConnectionString"].ConnectionString);
               SqlDataAdapter adp = new SqlDataAdapter("SELECT [CustomerID], WellID, SRB_RISK, APB_RISK  from [AMT].[dbo].bacteria where customerid = @cust order by 1", con);
               adp.SelectCommand.Parameters.AddWithValue("@cust", ddlCustomer.Text);
               adp.Fill(dt);

               if (dt.Rows.Count > 0)
               {
                   BacteriaGridview.DataSource = dt;
                   BacteriaGridview.DataBind();
               }
               else
               {
                   BacteriaGridview.DataSource = null;
                   BacteriaGridview.DataBind();
               }
           }
           catch (Exception ex)
           {
               Response.Write("Error Occured: " + ex.ToString());
           }
           finally
           {
               dt.Clear();
               dt.Dispose();
           }
       }