Update edited ComboBox items in database instead of adding them - sql

Question

I have a combobox named "Barcode", I fill it from database like this:
Sub fillIBarcode()
Barcode.DataSource = Nothing
Barcode.Items.Clear()
Dim adp As New SqlClient.SqlDataAdapter("Select distinct Barcode from Items where ItemCode=N'" & (ItemsDGV.CurrentRow.Cells(0).Value) & "'", SQlconn)
Dim ds As New DataSet
adp.Fill(ds)
Dim dt = ds.Tables(0)
'=====================================================
For I = 0 To dt.Rows.Count - 1
Barcode.Items.Add(dt.Rows(I).Item("Barcode"))
Barcode.SelectedIndex = 0
Next
End Sub
And it displays like that:
When the user edits and changes any numbers in the combobox and clicks the "Edit" button, how to submit this change and update the combobox items list immediately in the database?
I tried:
Private Sub Editbtn_Click(sender As Object, e As EventArgs) Handles Editbtn.Click
Dim cmdd As New SqlClient.SqlCommand
cmdd.Connection = SQlconn
cmdd.CommandText = "delete from Items where ItemCode=N'" & (ItemCode.Text) & "'"
cmdd.ExecuteNonQuery()
Dim sql = "select * From Items where ItemCode=N'" & (ItemCode.Text) & "'"
Dim adp As New SqlClient.SqlDataAdapter(sql, SQlconn)
Dim ds As New DataSet
adp.Fill(ds)
Dim dt = ds.Tables(0)
If dt.Rows.Count = 0 Then
For i = 0 To Barcode.Items.Count - 1
Dim dr = dt.NewRow
dr!ItemCode = ItemCode.Text
dr!Barcode = Barcode.Items(i).ToString
dt.Rows.Add(dr)
Next
Dim cmd As New SqlClient.SqlCommandBuilder(adp)
adp.Update(dt)
End If
End Sub
But it adds the new value, instead of updating the existing one.
I mean it added three barcodes, the original two, and the new edited one.

Answer 1

use SQL UPDATE QUERY :
you must conserve dt across form event to keep old value
dt has same index as combobox
declare dt as global in front of form code
Dim dt as datatable
in Sub fillIBarcode() remove DIM
dt = ds.Tables(0)
and in event handler execute an UPDATE query with ref to combobox selectedIndex:
Private Sub Editbtn_Click(sender As Object, e As EventArgs) Handles Editbtn.Click
Dim cmdd As New SqlClient.SqlCommand
cmdd.Connection = SQlconn
cmdd.CommandText = "UPDATE Items SET ItemCode=N'" & (ItemCode.Text) & "' WHERE ItemCode = N'" & dt.rows(Barcode.SelectedIndex).Item("Barcode") & "'"
cmdd.ExecuteNonQuery()
'update dt
dt.rows(Barcode.SelectedIndex).Item("Barcode") = ItemCode.Text
End Sub