Try this,Copy and replace this code
protected void DDLAieee_SelectedIndexChanged(object sender, EventArgs e)
{
DataSet ds = new DataSet();
ds = il.FetchDataById(2,DDLAieee.SelectedItem.ValueToString());
if (ds.Tables[0].Rows.Count > 0)
{
txtdescription.Text = ds.Tables[0].Rows[0][1].ToString();
}
}
public DataSet FetchDataById(int uid, string id)
{
DataAccess objDataAccess;
DataSet objResult;
objDataAccess = new DataAccess();
List objArrayList;
DbParameter objParamater;
objArrayList = new List();
objParamater = objDataAccess.NewParameter();
objParamater.ParameterName = "@uid";
objParamater.DbType = DbType.Int32;
objParamater.Direction = ParameterDirection.Input;
objParamater.Value = uid;
objArrayList.Add(objParamater);
objParamater = objDataAccess.NewParameter();
objParamater.ParameterName = "@id";
objParamater.DbType = DbType.VarChar;
objParamater.Direction = ParameterDirection.Input;
objParamater.Value = id;
objArrayList.Add(objParamater);
objResult = objDataAccess.ExecuteQuery("AieeeProc", objArrayList.ToArray());
return objResult;
}