Visual Basic

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
      Try
          If TxtUser.Text = Nothing Or TxtPassWord.Text = Nothing Then
              MsgBox("Veuillez renseigner tous les champs", MsgBoxStyle.Exclamation)
          Else
              If cnx.State = ConnectionState.Closed Then
                  cnx.Open()
              End If

              'VERIFER LES ENREGISTREMENTS DANS LA BASE DE DONNEE
              'cnx.Open()
              Dim searchQuery As String = "select count(*) from Admin WHERE RefAdmin=? and MotDePasse=?"
              Dim Command As New OleDbCommand(searchQuery, cnx)

              Command.Parameters.AddWithValue("@1", OleDbType.VarChar).Value = TxtUser.Text
              Command.Parameters.AddWithValue("@2", OleDbType.VarChar).Value = TxtPassWord.Text

              Dim count = Convert.ToInt32(Command.ExecuteScalar())

              If (count > 0) Then
                  MsgBox("Mot de passe validé avec succès'" & TxtUser.Text & "'", MsgBoxStyle.Information)
                  'DECLARATION DES VARIABLES
                  Dim motpass, nom, dateactive As String
                  motpass = TxtPassWord.Text
                  nom = TxtUser.Text
                  dateactive = DateAndTime.Now()
                  Dim insert2 As String = "INSERT INTO [PersonneActive] ([MotPasseActive], [NomActive], [DateActive]) VALUES (@motpass, @nom, @dateactive)"
                  Using cmd As New OleDbCommand(insert2, cnx)
                      'cmd.Parameters.AddWithValue("", 1)
                      cmd.Parameters.AddWithValue("@1", OleDbType.VarChar).Value = TxtPassWord.Text
                      cmd.Parameters.AddWithValue("@2", OleDbType.VarChar).Value = TxtUser.Text
                      cmd.Parameters.AddWithValue("@3", OleDbType.VarChar).Value = DateAndTime.Now()
                      'cmd.Parameters.AddWithValue("@confirmotpass", confirmotpass)
                      cmd.ExecuteNonQuery()
                  End Using
                  TxtUser.Text = ""
                  TxtPassWord.Text = ""
                  Me.Hide()
                  Form1.Show()
              Else
                  MsgBox("Problème avec le mot de passe ou Compte intouvable... Veuillez contacter l'administrateur AGO KOUAME BERTRAND", MsgBoxStyle.Critical)
                  TxtUser.Text = ""
                  TxtPassWord.Text = ""
              End If
          End If
          'Dim adapter As New OleDbDataAdapter(Command)
          'Dim ds As New DataSet
          'Dim table As New DataTable
          'adapter.Fill(ds, "CERTIFICAT")
          'DataGridView1.DataSource = ds.Tables("CERTIFICAT")

          'adapter.Dispose()
      Catch ex As Exception
          MsgBox(ex.Message)
      Finally
          cnx.Close()
      End Try
  End Sub

i am thinking of developing a restaurant billing system.

here is how my set up going to be.

1 desktop PC(SQLServer) to run SQL server. OS windows server.
2 desktop PCs(Cashier1,Cashier2) for cashiers.

SQLServer, Cashier1 and Cashier2 will be connected to local network(wired)

5 Tablet for waiters to take orders (enter orders to SQLServer). These Tablets will have wifi connections to enter customer orders into SQLServer

bills will be printed from Cashier1 and Cashier2

5 Tablets will be using unique user logins to take orders.

now my question is. will it be too slow or the system will hang when staffs use tablets to take orders?