This code is working fine....
SqlCommand cmd = new SqlCommand("select productid, productname + ' - ' + price as new from productinfo1", con1);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
con1.Close();
ddl.DataSource = ds;
ddl.DataTextField = "new";
ddl.DataValueField = "productid";
ddl.DataBind();
ddl.Items.Insert(0, new ListItem("--Select--", "0"));