Imports System.Data.SqlClient

Try
            Dim querystring As String = "SELECT MAX(pIDNo) FROM dbo.Patients"
   Using connection As New SqlConnection("Data Source=****;Initial Catalog=****;Persist Security Info=True;User ID=****;Password=****")
                Dim command As New SqlCommand(querystring, connection)
                connection.Open()
                Dim reader As SqlDataReader = command.ExecuteReader
                Dim value = String.Empty
                While reader.Read
                    value = reader.GetString(0)
                End While
                txtPNumber.Text = Today.Year.ToString().Substring(2, 2) & Today.Month.ToString().PadLeft(2, "0") & (Integer.Parse(value.Substring(4, value.Length - 4)) + 1).ToString("D4")
            End Using
        Catch ex As Exception
            txtPNumber.Text = Today.Year.ToString().Substring(2, 2) & Today.Month.ToString().PadLeft(2, "0") & num.ToString("D4")
        End Try