login once in vb.net using sql database

[aning0420]

hi !! my background in vb.net is not that good, but i need to make a voting system, user must be log in once and update his status into yes after voting, i have a table namely tbl_elemvoters it has a fields : voterid, username, password, name, grade, section and voted.
on the field voted, it contains 'no' , then after they login the field voted that contains no will updated to yes.

here is my code:

    conn.ConnectionString = "Server=localhost;User Id=root;Passsword=;Database=voting "


    Try
        conn.Open()

    Catch myerror As MySqlException
        MsgBox("error")

    End Try


    Dim myAdapter As New MySqlDataAdapter

    Dim myCommand As New MySqlCommand()
    myCommand.Connection = conn

    myAdapter.SelectCommand = myCommand

    If Textuser.Text = "" And Textpass.Text = "" Then
        MsgBox("invalid")
    ElseIf myCommand.CommandText = "SELECT * FROM tbl_elemvoters WHERE Username = '" + Textuser.Text + "' AND VoterID='" + Textpass.Text + "UPDATE Voted='" + "Yes"
            Form2.Show()
            Me.Hide()

update doesnt working, im confused ;'(.
thanks for the help

[artemix22]

what is adapter for? if you want to update your voted field you can do like this :

If Textuser.Text = String.Empty And Textpass.Text = String.Empty Then
            MsgBox("Invalid")
Else
            Try
                Using conn As New MySqlConnection("server=localhost;user=root;password=;database=voting")
                    conn.Open()
                    Dim command As New MySqlCommand("UPDATE tbl_elemvoters SET Voted = 'yes' WHERE Username = @Username AND VoterID = @VoterID", conn)
                    With command.Parameters
                        .AddWithValue("@Username", Textuser.Text)
                        .AddWithValue("@VoterID", Textpass.Text)
                    End With
                    command.ExecuteNonQuery()
                    command.Dispose()
                    conn.Close()
                    Form2.Show()
                    Me.Hide()
                End Using
            Catch ex As Exception
                MsgBox(ex.Message)
            End Try
End If

[Keerthi_1]

Hi