Imports MySql.Data.MySqlClient
Imports System.Security.Cryptography
Public Class Form1
    Dim conn As New MySqlConnection
    Dim myCommand As New MySqlCommand
    Dim myAdapter As New MySqlDataAdapter
    Dim myData As New DataTable
    Dim SQL As String
    Dim SQLRem As String
    Dim nome As String
    Dim passhash As String
    Dim passhashlc As String
    Dim Response As MsgBoxResult
    Private Function GeraMD5(ByVal texto As String) As String
        Dim provider As New MD5CryptoServiceProvider
        Dim bytHash() As Byte
        Dim hash As String = String.Empty
        bytHash = provider.ComputeHash(System.Text.Encoding.UTF8.GetBytes(texto))
        provider.Clear()
        hash = BitConverter.ToString(bytHash).Replace("-", String.Empty)
        Return hash
    End Function

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim conn As MySqlConnection
        conn = New MySqlConnection
        'Informações do servidor do Banco de Dados
        conn.ConnectionString = "server=localhost;user id=root;password=;database=authdb"
        'Query para selecionar usuário
        SQL = "SELECT * FROM authdb_users WHERE username ='" & txtBox.Text & "'"
        'Query para deletar usuário
        SQLRem = "DELETE FROM authdb_users WHERE username ='" & txtBox.Text & "' AND password ='" & passhashlc & "'"

        Try
            'Limpar data para loop
            myData.Rows.Clear()
            'Abrir conexão
            conn.Open()
            'Gerar hash MD5 da senha
            passhash = GeraMD5(TextBox1.Text)
            'Transformar para LowerCase
            passhashlc = LCase(passhash)
            'Executar Query MySQL
            myCommand.Connection = conn
            myCommand.CommandText = SQL
            myAdapter.SelectCommand = myCommand
            'Preencher data
            myAdapter.Fill(myData)
            'Setar DataGrid para Data
            DataGridView1.DataSource = myData
            'Checar se Grid está vazio
            If IsNothing(DataGridView1.CurrentRow) Then
                'Caso não encontrado
                MsgBox("Usuário não encontrado!")
            Else
                'Caso encontrado
                MsgBox("Usuário encontrado!")

                Response = MsgBox("Deseja remover usuário?", MsgBoxStyle.YesNo)
                If Response = MsgBoxResult.Yes Then
                    Try
                        myCommand.Connection = conn
                        myCommand.CommandText = SQLRem
                        myAdapter.SelectCommand = myCommand
                        myAdapter.Fill(myData)

                        Try
                            myData.Rows.Clear()
                            myCommand.Connection = conn
                            myCommand.CommandText = SQL

                            myAdapter.SelectCommand = myCommand
                            myAdapter.Fill(myData)
                            DataGridView1.DataSource = myData
                            conn.Close()
                            If IsNothing(DataGridView1.CurrentRow) Then

                                MsgBox("Usuário removido com sucesso!")
                            Else
                                MsgBox("Ocorreu algum erro durante a remoção e usuário não foi removido! Contate Administração")
                            End If

                        Catch ex As MySqlException
                            MsgBox(ex.Message)
                        End Try


                    Catch ex As MySqlException
                        MsgBox(ex.Message)
                    End Try
                End If


            End If

        Catch myerror As MySqlException
            MsgBox("There was an error reading from the database: " & myerror.Message)
        End Try
        conn.Dispose()
        conn.Close()

    End Sub
End Class