Problem with updating MySQL table using DataGridView (no replies)

Hi all,

I am quite new to Vb.NET. What I was trying to do is getting information from database table into a datagridview and save the changes back to database table.

I did the first step running. But when I make changes on the datagridview field and click "Save Changes" button, my message of "1 records updated" appears but all fields in the database changes to NULL values.

Can anyone see the problem on the code below. Please send your replies with details and examples as it is very hard for me to understand as I am a newbie

Thanks very much
Ceyhun

**** This section is under Form1 class 


Dim cn As New MySqlConnection("Data Source=localhost;Database=stokprogrami;User ID=root;Password=;")
    Dim adapter As New MySqlDataAdapter
    Dim command As New MySqlCommand
    Dim dtListe As New DataTable()

**** This section adds the data to datagridview on change of a combobox


   Private Sub cihazmodeli_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cihazmodeli.SelectedIndexChanged
        'Datagridview'e girilir.
        If Not CStr(cihazmodeli.SelectedItem.Value) = "" Then
            Dim sorgu As String = "Select serinumarasi,garantisuresi,faturatarihi,servicetag,macid1,macid2,winlisans1,winlisans2 from stoklar where modelID='" & CStr(cihazmodeli.SelectedItem.Value) & "'"
            command.CommandText = sorgu
            command.Connection = cn
            adapter.SelectCommand = command
            adapter.Fill(dtListe)
            mevcutcihazlar.DataSource = dtListe
            cn.Close()
            mevcutcihazlar.Columns(0).HeaderText = "Seri Numarasi"
            mevcutcihazlar.Columns(1).HeaderText = "Garanti Süresi"
            mevcutcihazlar.Columns(2).HeaderText = "Fatura Tarihi"
            mevcutcihazlar.Columns(3).HeaderText = "Service Tag"
            mevcutcihazlar.Columns(4).HeaderText = "Mac ID 1"
            mevcutcihazlar.Columns(5).HeaderText = "Mac ID 2"
            mevcutcihazlar.Columns(6).HeaderText = "Win Lisans 1"
            mevcutcihazlar.Columns(7).HeaderText = "Win Lisans 2"
            mevcutcihazlar.Visible = True
        Else
            mevcutcihazlar.DataSource = ""
            mevcutcihazlar.Visible = False
        End If
    End Sub

**** this section is the event of click "Save Changes" 
Private Sub savechanges_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles savechanges.Click
 If Not dtListe.GetChanges() Is Nothing Then
       
 	Dim update As New MySqlCommand("UPDATE stoklar SET serinumarasi = @serinumarasi, garantisuresi = @garantisuresi, faturatarihi = STR_TO_DATE(@faturatarihi,'%d.%m.%Y'), servicetag = @servicetag, macid1 = @macid1, macid2 = @macid2, winlisans1 = @winlisans1, winlisans2 = @winlisans2", cn)
        update.Parameters.Add("@serinumarasi", MySqlDbType.VarChar, 255, "serinumarasi")
        update.Parameters.Add("@garantisuresi", MySqlDbType.Int16, 3, "garantisuresi")
        update.Parameters.Add("@faturatarihi", MySqlDbType.String, 255, "faturatarihi")
        update.Parameters.Add("@servicetag", MySqlDbType.VarChar, 50, "servicetag")
        update.Parameters.Add("@macid1", MySqlDbType.VarChar, 50, "macid1")
        update.Parameters.Add("@macid2", MySqlDbType.VarChar, 50, "macid2")
        update.Parameters.Add("@winlisans1", MySqlDbType.VarChar, 50, "winlisans1")
        update.Parameters.Add("@winlisans2", MySqlDbType.VarChar, 50, "winlisans2")
        adapter.UpdateCommand = update
        cn.Close()
        Dim guncellenen As Integer = adapter.Update(dtListe)
        MessageBox.Show(guncellenen & " kayit güncellendi.")
 End If

    End Sub