ทำหน้า login แต่จะตรวจสอบกับ sql server 2005 user ที่กำนหด ในเมนู security --> login

Public strcon As String = "Server=server2005;Database=csw57;User Id=sa;Password=1234;" 

Imports System.Data.SqlClient
Public Class Login
    Dim cn As SqlConnection
    Dim da As SqlDataAdapter
    Dim dt As DataTable
    Dim sql As String = ""
    Sub selectdata()
        sql = "SELECT * FROM sys.server_principals WHERE name = '" & TxtUser.Text.Trim & "'"
        da = New SqlDataAdapter(sql, cn)
        dt = New DataTable
        da.Fill(dt)
        Dim dr As DataRow = dt.NewRow
        If dt.Rows.Count > 0 Then
            MsgBox("เชื่อมต่อได้")
        Else
            MsgBox("เชื่อมต่อไม่ได้")
        End If
    End Sub

    Private Sub Login_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        cn = New SqlConnection
        With cn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = Module1.strcon
            .Open()
        End With
    End Sub
    Private Sub BnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BnLogin.Click
        Me.selectdata()
    End Sub
End Class

 cn = New SqlConnection
        With cn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = Module1.strcon1
            .Open()
        End With

        Try
            cn = New SqlConnection
            With cn
                If .State = ConnectionState.Open Then .Close()
                .ConnectionString = Module1.strcon1
                .Open()
                Dim Home As New Home
                Home.Show()
            End With
        Catch ss As Exception
            MsgBox(ss.Message)
        End Try