-Object reference not set to an instance of an object

Question

Guys when i run the code below i get this error:-Object reference not set to an instance of an object. everything is initialized and there are no empty fields in the database please help !

Dim con As New OleDbConnection

        Dim cmd2 As New OleDbCommand
        con.ConnectionString = ("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\mydb.accdb")

        cmd2.CommandText = "update items set itmbrcd=@p5,itemname=@p1,itemprice=@p2,itemGroup=@group,remarks=@p3,vat=@p6 where itmcode=@p4"
        cmd2.Connection = con
        con.Open()

        cmd2.Parameters.AddWithValue("@p5", ItmBrcdTextBox.Text)
        cmd2.Parameters.AddWithValue("@p1", ItemNameTextBox.Text)
        cmd2.Parameters.AddWithValue("@p2", ItemPriceTextBox.Text)
        cmd2.Parameters.AddWithValue("@group", ItemGroupComboBox.SelectedItem.ToString)
        cmd2.Parameters.AddWithValue("@p3", RemarksTextBox.Text)
        cmd2.Parameters.AddWithValue("@p4", ItmcodeTextBox.Text)
        cmd2.Parameters.AddWithValue("@p6", VatNumericUpDown.Value)

        cmd2.ExecuteNonQuery()
        MsgBox("item updated!")
        con.Close()

P.S. it stopped working when i added the "vat" field to the database, everything was normal before and the insert and delete are working — charles, Dec 19 '15 at 20:57
The line it happens on should tell you a lot. My guess is that nothing is selected in the ComboBox. You add the last few params in the wrong order too. — Ňɏssa Pøngjǣrdenlarp, Dec 19 '15 at 21:02
Possible duplicate of [What is a NullReferenceException and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — marc_s, Dec 19 '15 at 21:11
@plutonix debugging the lines returned no error, think problems updating the dataset — charles, Dec 19 '15 at 21:27

score 0 · Answer 1 · answered Dec 20 '15 at 02:34

0

As Plutonix mentioned, you get this error on the following line when nothing is selected in the combo box. Check to see if combo1.SelectedItem is nothing.

cmd2.Parameters.AddWithValue("@group", ItemGroupComboBox.SelectedItem.ToString)

answered Dec 20 '15 at 02:34

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-Object reference not set to an instance of an object

1 Answers1