My thesis (Online Billing and Reservation System)

Imports System.Data.SqlClient
Imports System.Text.RegularExpressions
Partial Class html_Default
    Inherits System.Web.UI.Page
    Public con As New SqlConnection("Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Thesis\App  _Data\JPDatabase.mdf;Integrated Security=True;User Instance=True")


    Function EmailAddressCheck(ByVal emailAddress As String) As Boolean
        Dim pattern As String = "^[a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$"
        Dim emailAddressMatch As Match = Regex.Match(emailAddress, pattern)
        If emailAddressMatch.Success Then
            EmailAddressCheck = True
        Else
            EmailAddressCheck = False
        End If
    End Function

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        con.Open()
        Dim c As String
        c = "Select * from register where email = '" & Session("email") & "'"
        Dim com As New SqlCommand(c, con)
        Dim dr As SqlDataReader
        dr = com.ExecuteReader
        If dr.HasRows Then
            dr.Read()
            Label1.Text = dr("title")
            Label2.Text = dr("fname")
            Label3.Text = dr("surname")
            Label4.Text = dr("email")

            DropDownList1.SelectedItem.Text = dr("title")
            TextBox1.Text = dr("surname")
            TextBox2.Text = dr("fname")
            TextBox3.Text = dr("email")

            TextBox4.Text = dr("alemail")


        End If
        con.Close()
    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        con.Open()
        Dim a As String
        a = "Update register set  mbirth = '" & DropDownList2.Text & "', dbirth = '" & TextBox12.Text & "', ybirth = '" & TextBox13.Text & "',gender = '" & DropDownList3.Text & "',alphone = '" & TextBox11.Text & "',phone = '" & TextBox10.Text & "',postal= '" & TextBox9.Text & "',state = '" & TextBox8.Text & "',country = '" & TextBox7.Text & "', city = '" & TextBox6.Text & "', mailadd = '" & TextBox5.Text & "', mailtype = '" & DropDownList6.Text & "',  title = '" & DropDownList1.Text & "' , alemail = '" & TextBox4.Text & "' where email = '" & Session("email") & "'"
        Dim com As New SqlCommand(a, con)
        com.ExecuteNonQuery()
        Response.Redirect("customerpersonal.aspx")
        con.Close()
    End Sub

End Class