ASP.NET

public List<KeyValuePair<string, string>> GetCategories()
{
     //Pseudo-Code
     //Open Database Connection
     //Create a command of type StoredProcedure
     //Tell the command which stored procedure to execute (preferrably, your "GetCategories() SP)
     List<KeyValuePair<string,string>> categories = new List<KeyValuePair<string,string>>();
     while(reader.Read())
     {
           categories.Add(new KeyValuePair<string,string>(reader["CategoryName"],reader["categoryID"].ToString());
     }
 return categories;
}

public List<BusinessObject> GetData(int category)
{
     //Pseudo-Code
     //Open Database Connection
     //Create a command of type StoredProcedure
     //Tell the command which stored proc to execute (preferrably, the one that "Gets Data")
     //Send category down to Stored Proc as a parameter
     List<BusinessObject> list = new List<BusinessObject>();
     while(reader.Read())
     {
          list.Add(new BusinessObject(reader["id"],reader["blahdeblah"],reader["whateverotherfieldyouwanttomap"]);
     }
     return list;
}


protected void Page_Load(object sender, EventArgs e)
{
   if(!Page.IsPostBack)
   {
      grdData.DataSource = GetData();
      grdData.DataBind();
      ddlCategories.DataSource = GetCategories();
      ddlCategories.DataTextField = "Key";
      ddlCategories.DataValueField = "Value";
      ddlCategories.DataBind();
   }
}