Imports System.Windows.Forms
Imports System.Data.SqlClient
Imports System.Data.SqlClient.SqlConnection
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim ConnString As String = "Data Source=MARCELLA-PC;Initial Catalog=superclean;User Id=sa;Password=fabio;"
Dim sqlcon As New SqlConnection(ConnString)
Dim sql As String = "SELECT USERNAME,PASSWORD FROM UTENTI WHERE USERNAME=@USERN AND PASSWORD=@PASSW"
Dim cmd As New SqlCommand(sql, sqlcon)
Dim user As String
Dim pass As String

cmd.Parameters.Add("@USERN", SqlDbType.Text)
cmd.Parameters("@USERN").Value = user
cmd.Parameters.Add("@PASSW", SqlDbType.Text)
cmd.Parameters("@PASSW").Value = pass
sqlcon.Open()
cmd.ExecuteReader()
sqlcon.Close()