如何将组合框值设置为从空开始 [英] How do you set the combo box value to start from empty

问题描述

这是我的代码：

Hi,

Here is my code:

m_dtDelayedDeliveryDays = GetDelayedDeliveryDays()
        cmbDelayedDeliveryDays.SelectedIndex = -1

        For Each dr As DataRow In m_dtDelayedDeliveryDays.Rows
            Me.cmbDelayedDeliveryDays.Items.Add(dr("DeliveryDelayDays"))
        Next
        cmbDelayedDeliveryDays.DataSource = m_dtDelayedDeliveryDays
        cmbDelayedDeliveryDays.DisplayMember = "DeliveryDelayDays"
        cmbDelayedDeliveryDays.ValueMember = "DeliveryDelayDaysID"

        Dim delayID As Integer = m_objUIMgr.DeliveryDelayDaysID

        If delayID > 0 Then


            cmbDelayedDeliveryDays.SelectedIndex = delayID - 1



        End If

        'delayID = Nothing

My combo box has values like 0,3,7...When the form gets loaded it shud display empty.


    End Sub

我正在尝试从数据库加载我的组合值。另外，我检查值是否在数据库中已经在行中

Dim delayID As Integer = m_objUIMgr.DeliveryDelayDaysID ...如果之前没有存储ID，则返回0.



以上代码在检索时工作正常。但是当数据表中没有ID时，我的组合框默认显示为0而不是空。请帮助。

I am trying to load my combo value from the database. Also i check whether the values are in the database already in the line
Dim delayID As Integer = m_objUIMgr.DeliveryDelayDaysID...This will return 0 if there is no ID stored before.

The above code works fine on retrieving . But when there is no ID in the datatable then my combo box displays by default value 0 instead of empty.Please help.

推荐答案

hi，

在上面的代码中，您检查了条件



如果delayID> 0然后



cmbDelayedDeliveryDays.SelectedIndex = delayID - 1





结束如果



和你说

Dim delayID As Integer = m_objUIMgr.DeliveryDelayDaysID



它返回为0。

因此，条件为假。然后这个编码将如何工作？



您可以尝试：

如果delayID> = 0那么



cmbDelayedDeliveryDays.SelectedIndex = delayID - 1





结束如果

In the above code, you have checked condition that

If delayID > 0 Then

cmbDelayedDeliveryDays.SelectedIndex = delayID - 1


End If

and you said
Dim delayID As Integer = m_objUIMgr.DeliveryDelayDaysID

it returns as "0".
Hence, Condition is false. then how this coding will work?

You can try like:
If delayID >= 0 Then

cmbDelayedDeliveryDays.SelectedIndex = delayID - 1


End If

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