如何在组合框中为每个省获得1个值 [英] How do I get 1 value for each province in combobox

问题描述

当我选择区域时，它显示以下区域，当我去省时，它显示了很多省，例如.cebu它显示所有宿务在组合框中

我想要的只有1宿务将在组合框中看到而不是许多宿务。与城市同桌



我尝试过：

when i select region it shows the following region and when i go to province it shows a lot of province repeatedly like for example.cebu it shows all cebu in combobox
all i want is only 1 cebu will see in combobox instead of many cebu. thesame with city

What I have tried:

Private Sub cboRegion_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboRegion.SelectedIndexChanged
        Dim oledr As OleDb.OleDbDataReader
        Connection = "select * from Address where Region = '" & cboRegion.Text & "'"
        cboProvince.Items.Clear()
        Dim acscmd As New OleDb.OleDbCommand
        acscmd.CommandText = Connection
        acscmd.Connection = OleCn
        oledr = acscmd.ExecuteReader()

        While (oledr.Read())
            cboProvince.Items.Add(oledr("Province"))
        End While
        cboProvince.SelectedIndex = -1
        acscmd.Dispose()
        oledr.Close()
    End Sub

Private Sub cboProvince_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboProvince.SelectedIndexChanged
        Dim oledr As OleDb.OleDbDataReader
        Connection = "select * from Address where Province = '" & cboProvince.Text & "'"
        cboCity.Items.Clear()
        Dim acscmd As New OleDb.OleDbCommand
        acscmd.CommandText = Connection
        acscmd.Connection = OleCn
        oledr = acscmd.ExecuteReader()

        While (oledr.Read())

            cboCity.Items.Add(oledr("City"))

        End While
        cboCity.SelectedIndex = -1

        acscmd.Dispose()
        oledr.Close()
    End Sub

Private Sub cboCity_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboCity.SelectedIndexChanged
       Dim oledr As OleDb.OleDbDataReader
       Connection = "select * from Address where City = '" & cboCity.Text & "'"
       cboBrgy.Items.Clear()
       Dim acscmd As New OleDb.OleDbCommand
       acscmd.CommandText = Connection
       acscmd.Connection = OleCn
       oledr = acscmd.ExecuteReader()
       While (oledr.Read())
           cboBrgy.Items.Add(oledr("Barangay"))
       End While
       cboBrgy.SelectedIndex = -1
       acscmd.Dispose()
       oledr.Close()

   End Sub

推荐答案

您是否检查过sql字符串是否使用了正确的值？

Did you check if the sql string uses the correct values?

sql = "select * from Address where City = '" & cboCity.Text & "'"

我实际上并不是100％确定，但是在服务器控件完成之前，我执行了SelectedIndexChange-Event。



因此，请检查程序中cboCity.Text是否为空。

如果是emtyp，请尝试使用以下内容：

I'm not 100% sure actually, but I thnk the SelectedIndexChange-Event is executed BEFORE the server controls are finished.

So check if cboCity.Text is empty in the procedure.
If it's emtyp try to use the follwing:

sql = "select * from Address where City = '" &  Request.Form("cboCity") & "'"

（将cboCity替换为控件的正确名称 - >请参阅在运行时断点的immidiate窗口中的Request.Form.AllKeys（））

(Replace "cboCity" with the correct name of the control -> see Request.Form.AllKeys() in the immidiate window at runtime break)

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