.vb class for transaction sql

Imports System
Imports System.Data
Imports System.Configuration
Imports System.Data.SqlClient
Public Class clsConnection
    Public Sub New()
        '
        ' TODO: Add constructor logic here
        '
    End Sub
    Dim con As SqlConnection = New SqlConnection()
    Dim com As SqlCommand = New SqlCommand()
    Dim da As SqlDataAdapter = New SqlDataAdapter()
    Dim constr As String = "Data Source=servernaem\SQLEXPRESS;Initial Catalog=dbname  

    Public Function selectds(ByVal str As String) As DataSet
        Dim ds As DataSet = New DataSet()
        If con.State = ConnectionState.Closed Then
            con.ConnectionString = constr
            con.Open()
        End If
        com.CommandText = str
        com.Connection = con
        da.SelectCommand = com
        da.Fill(ds)
        con.Close()
        Return ds
    End Function

End Class