vb.net kann keine Verbindung zu mysql

Question

Ich habe versucht, auf Login-System mit MySQL zu erstellen. aber ich weiß nicht, dass es nicht funktioniert. Es gibt mein Versuch jedes Mal, wenn das Problem ist?

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
    mysqlconn = New MySqlConnection 
    mysqlconn.ConnectionString = "server=localhost;userid=root;password=;database=tes" 
    Dim reader As MySqlDataReader 

    Try 
     mysqlconn.Open() 
     Dim query As String = "select * from kullanicilar where 'username=" & TextBox1.Text & "' and 'password=" & TextBox2.Text & "'" 
     komut = New MySqlCommand(query, mysqlconn) 
     reader = komut.ExecuteReader 
     Dim girdimi As Integer = 0 

     If reader.Read Then 
      girdimi = girdimi + 1 
     End If 

     If girdimi = 1 Then 
      Form2.Show() 
     ElseIf girdimi = 0 Then 
      MessageBox.Show("try again") 
     End If 
     mysqlconn.Close() 
    Catch ex As MySqlException 
     MessageBox.Show(ex.Message) 
    Finally 
     mysqlconn.Dispose() 

    End Try 
End Sub 

Answer 1

es auf diese Weise versuchen (basierend auf Datareader MSDN article):

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
    mysqlconn = New MySqlConnection 
    mysqlconn.ConnectionString = "server=localhost;userid=root;password=;database=tes" 
    Dim reader As MySqlDataReader 

    Try 
     mysqlconn.Open() 
     Dim query As String = "select * from kullanicilar where username='" & TextBox1.Text & "' and password='" & TextBox2.Text & "'" 
     komut = New MySqlCommand(query, mysqlconn) 
     reader = komut.ExecuteReader() 
     Dim girdimi As Integer = 0 

     If reader.HasRows Then 
      Do While reader.Read() 
       girdimi = girdimi + 1 
       If girdimi = 1 Then 
        Form2.Show() 
       ElseIf girdimi = 0 Then 
        MessageBox.Show("try again") 
       End If 
     Loop 
     End If 

     mysqlconn.Close() 
    Catch ex As MySqlException 
     MessageBox.Show(ex.Message) 
    Finally 
     mysqlconn.Dispose() 

    End Try 
End Sub