พี่ๆคับ ช่วยดู code login ให้ผมทีคับ ด่วนมากคับงานผมไม่เดินเลย

Imports MySql.Data.MySqlClient
Imports MySql.Data
Imports System.Data

Public Class fmlogin
    Dim sql As String = "Server=localhost;User Id=root; Password=1234; Database=shop_management_system;"
    Dim conn As New MySqlConnection
  

    Private Sub btnclose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnclose.Click
        Close()
    End Sub

  

    Private Sub btnregistry_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnregistry.Click
        fmregistry.Show()
        Me.Hide()
    End Sub
  
    Private Sub btnlogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnlogin.Click



        conn.ConnectionString = sql

        conn.Open()



        Try


            If Me.txtusername.Text = "" Or Me.txtpass.Text = "" Then
                MsgBox("กรุณากรอกชื่อผู้ใช้งานและรหัสผ่าน", MsgBoxStyle.Exclamation, "Error")
                txtusername.Clear()
                txtpass.Clear()
                Me.txtusername.Focus()



            End If


            If txtusername.Text <> "" And txtpass.Text <> "" Then

                Dim cm As New MySqlCommand("select * from login where Username=" & "'" & txtusername.Text & "' and pass=" & "'" & txtpass.Text & "'", conn)


                Dim Rd As MySqlDataReader

                Dim User As String
                Dim Pass As String

                Dim firstname As String
                Dim lastname As String


                Rd = cm.ExecuteReader
                Rd.Read()
                User = Rd.Item("Username")
                Pass = Rd.Item("pass")
                firstname = Rd.Item("Firstname")
                lastname = Rd.Item("Lastname")




                If txtusername.Text = User And txtpass.Text = Pass Then


                Dim insert As New MySqlCommand

                    Dim dd As String = " INSERT INTO [Checkuser] (Status,Username,Firstname,Lastname ) " & _
                                    "SELECT Status,Username,Firstname,Lastname FROM Login WHERE Username='" & User & "' and Firstname='" & firstname & "' and Lastname='" & lastname & "'"





                    insert.CommandType = CommandType.Text
                    insert.CommandText = dd
                    insert.Connection = conn
                    insert.ExecuteNonQuery()


                    fmshop.Text = firstname
                    fmshop.Show()

                    Me.Hide()



                End If
            End If

        Catch ex As Exception

            If txtusername.Text = "admin" And txtpass.Text = "admin" Then

                fmshop.tsmadmin.Visible = True
                fmshop.Show()
                txtusername.Text = ""
                txtpass.Text = ""
                Me.Hide()
            Else

                MsgBox("คุณไม่มีสิทธิ์เข้าใช้ระบบนะครับ T-T")

            End If

            Exit Sub
            conn.Close()
        End Try


    End Sub


End Class