Listing 1: Using a SqlDataReader to Return Rows from a Query and Close the Connection.
       Dim sngLeak as Single  
        Try		' Trap exceptions during this routine.
            ' Capture the number of pooled connections.
            sngLeak = pcPooledConnections.NextValue
            ' Create a new DataReader.
            Dim dr as SqlDataReader
            Dim i as Integer
            Dim strAuID as String
            lblConnections.Text = "0"
 [BEGIN CALLOUT A]
        For i = 1 To 110
          Dim cn As New SqlConnection("server=.;" _
& "integrated security=true;max pool size=10")
          Dim cmd As New SqlCommand("SELECT TOP 5 au_id" _
& " FROM pubs..authors", cn)
          lblConnections.Text = i.ToString  ' Show connection count.
          lblRtn.Text = (i.ToString)
          cn.Open()    ' DataReader requires a pre-opened connection.
[END CALLOUT A]
[BEGIN CALLOUT B]
            If cbCBCmdBehavior.Checked Then
              dr = cmd.ExecuteReader(CommandBehavior.CloseConnection)
            Else
              dr = cmd.ExecuteReader()
            End If
[END CALLOUT B]
[BEGIN CALLOUT C]
    If cbUseGrid.Checked Then
                    DataGrid1.DataSource = dr
                    DataGrid1.DataBind()
          Else
                    DataGrid1.DataSource = Nothing
                    While dr.Read
                        strAuID = dr.GetValue(0).ToString
                    End While
         End If
[END CALLOUT C]
[BEGIN CALLOUT D]
     If cbCloseConnection.Checked Then
        cn.Close() ' This should be enough; it closes the connection.
     Else
        ' Don't manually close the connection.
        ' This should cause a leak if the connection isn't closed elsewhere.
     End If
     If cbCloseDataReader.Checked Then
        dr.Close()
     Else
       ' Don't manually close the connection.
       ' This might cause a leak.
     End If
     lblPooledConnections.Text = pcPooledConnections.NextValue.ToString
     lblUserConnections.Text = pcUserConnections.NextValue.ToString
   Next i
   lblRtn.Text &= "<BR>" & "All 110 operations complete."
[END CALLOUT D]
[BEGIN CALLOUT E]
Catch exI As System.InvalidOperationException
  lblRtn.Text &= "<BR>" & "Could not open connection: " _
   & exI.Message
 Catch ex As Exception		' Unexpected exceptions
   lblRtn.Text &= "<BR>" & (ex.ToString)
 Finally
     ' Calculate the number of additional pooled connections created. 
     ' This number should be 0.
   lblLeaks.Text = (pcPooledConnections.NextValue - sngLeak).ToString
   lblRtn.Text &= ("<BR>" & "Done")
 End Try
End Sub
[END CALLOUT E]