Question

I have the following code to populate a dropdownlist:

string strConn = ConfigurationManager.ConnectionStrings["PhoQL"].ConnectionString;
using (SqlConnection con = new SqlConnection(strConn))
{
  DataSet ds = new DataSet();
  using (SqlDataAdapter myda = new SqlDataAdapter("SELECT [Abrv], [State] FROM [States]", con))
  {
    myda.Fill(ds)
    ddlShipState.DataSource = ds;
  }
}
ddlShipState.DataTextField = "State";
ddlShipState.DataValueField = "Abrv";
ddlShipState.DataBind();

I was wondering if there is a more efficient way of doing it. Notice I didn’t have to open and close the connection. Wondering if it makes a difference in my example.
In terms of more efficient I am looking for best code practice for what I have above.

Answer 1

Notice I didn’t have to open and close the connection.

No, but the DataAdapter does it implicitely.

MSDN:

If the IDbConnection is closed before Fill is called, it is opened to
retrieve data and then closed. If the connection is open before Fill
is called, it remains open.

But also note that opening and closing is not inefficient when you’re using Connection-Pooling(default). Because then con.Open just means “wait, i need this connection now” and con.Close means “ok, you can reuse it somewhere else now, i’m finished”.

So you should always close a connection as soon as you’re finished with it. Otherwise the connection-pool needs to open new physical connections everytime which can cause exceptions(maximum default connection count is 100) but always will decrease the performance.

The best way to dispose/close connections(any IDisposable) is by using the using statement:

using(var con = new SqlConnection(ConfigurationManager.ConnectionStrings["PhoQL"].ConnectionString))
using(var cmd = new SqlCommand("SELECT [Abrv], [State] FROM [States]", con))
using(var da = new SqlDataAdapter(cmd))
{
    DataTable tbl = new DataTable();
    da.Fill(tbl);
    ddlShipState.DataSource = tbl;
    ddlShipState.DataTextField = "State";
    ddlShipState.DataValueField = "Abrv";
    ddlShipState.DataBind();
} 

(sidenote: i’ve replaced your DataSet with a “lighter” DataTable)