Question

Sub CboSO_DropDown(ByVal sender As Object, ByVal e As System.EventArgs) Handles CboSO.DropDown
    If functionmode = "UPDATE" Then
        Dim daProp2 As New OdbcDataAdapter()
        Dim dsProp2 As New DataSet()
        Dim qryProp2 As String


        qryProp2 = "SELECT * FROM so WHERE scn = '" & txtSCN.Text & " 'AND shutout_ind <> 'N' and so.reload_ind='N' and so.redelv_ind='N'"
        daProp2.SelectCommand = New OdbcCommand(qryProp2, conn)
        Dim cb2 As OdbcCommandBuilder = New OdbcCommandBuilder(daProp2)
        daProp2.Fill(dsProp2, "so")
        Dim dtRbt As DataTable = dsProp2.Tables("so")


        If dsProp2.Tables(0).Rows.Count > 0 Then
            CboSO.DataSource = dtRbt
            CboSO.DisplayMember = "so_num"

        End If

    End If

End Sub

Private Sub CboSO_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles CboSO.KeyPress
    Dim daProp3 As New OdbcDataAdapter()
    Dim dsProp3 As New DataSet()
    Dim qryProp3 As String


    qryProp3 = "SELECT SUM(item_num) as totitemnum FROM soitem WHERE scn= '" & txtSCN.Text & " 'AND so_num='" & CboSO.SelectedItem & "' "
    daProp3.SelectCommand = New OdbcCommand(qryProp3, conn)
    Dim cb3 As OdbcCommandBuilder = New OdbcCommandBuilder(daProp3)
    daProp3.Fill(dsProp3, "soitem")
    Dim dtRbt As DataTable = dsProp3.Tables("soitem")


    If dsProp3.Tables(0).Rows.Count > 0 Then
        LblSOQty.Text = IIf(IsDBNull(dsProp3.Tables(0).Rows(0)("totitemnum")), "", dsProp3.Tables(0).Rows(0)("totitemnum"))

    End If

End Sub

Answer 1

You have to use CboSO.SelectedValue or CboSO.Text property instead of Cbo.SelectedItem.

PS: Use Parameter (prepare) instead of hard-coded sql string.