Question

我在互联网上找到了几个例子来做这个但是真的很难让它在VB中运行。（试过一个转换器但结果好坏）

我需要根据第一个下拉列表中的不同值填充下拉列表的选项。

任何人都可以帮助VB中的一个简单的例子吗？如果值在脚本中被“硬编码”，则不会引起争议。或者从表中提取数据的SQL位

提前致谢！

Answer 1

它的完成方式是在第一个下拉菜单的SelectedIndexChanged事件中填充第二个下拉列表

Protected Sub ddlCountry_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
    Dim CountryID As Integer = Convert.ToInt32(ddlCountry.SelectedValue.ToString())
    FillStates(CountryID)
End Sub


Private Sub FillStates(ByVal countryID As Integer)
  Dim strConn As String = ConfigurationManager.ConnectionStrings("DatabaseConnectionString").ConnectionString
  Dim con As New SqlConnection(strConn)
  Dim cmd As New SqlCommand()
  cmd.Connection = con
  cmd.CommandType = CommandType.Text
  cmd.CommandText = "Select StateID, State from State where CountryID =@CountryID"
  cmd.Parameters.AddWithValue("@CountryID", countryID)
  Dim objDs As New DataSet()
  Dim dAdapter As New SqlDataAdapter()
  dAdapter.SelectCommand = cmd
  con.Open()
  dAdapter.Fill(objDs)
  con.Close()
  If objDs.Tables(0).Rows.Count > 0 Then
    ddlState.DataSource = objDs.Tables(0)
    ddlState.DataTextField = "State"
    ddlState.DataValueField = "StateID"
    ddlState.DataBind()
    ddlState.Items.Insert(0, "--Select--")
  Else
    lblMsg.Text = "No states found"
  End If
 End Sub

使用html源代码：

   <asp:DropDownList ID="ddlState" runat="server" AutoPostBack="True">
  </asp:DropDownList>

  <asp:DropDownList ID="ddlCountry" runat="server" 
  AutoPostBack="True" OnSelectedIndexChanged="ddlCountry_SelectedIndexChanged">
 </asp:DropDownList>

Answer 2

您可以在ASPX页面中以声明方式完成此操作：

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:myConnString %>" SelectCommand="SELECT id, name FROM planets"></asp:SqlDataSource>
<asp:DropDownList ID="ddlPlanets" AutoPostBack="true" DataTextField="name" DataValueField="id" DataSourceID="SqlDataSource1" runat="server" AppendDataBoundItems="true" />

<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:myConnString %>" SelectCommand="SELECT planetid, name FROM moons" FilterExpression="planetid = '{0}'">
    <FilterParameters>
        <asp:ControlParameter Name="planetid" ControlID="ddlPlanets" PropertyName="SelectedValue" />
    </FilterParameters>
</asp:SqlDataSource>      
<asp:DropDownList ID="ddlMoons" DataTextField="name" DataValueField="planetid" DataSourceID="SqlDataSource2" runat="server" />

Answer 3

您最好的选择是在第一个下拉列表上捕获SelectedIndexChanged事件，检查下拉列表的当前值是什么，然后使用清除然后填充第二个下拉列表中的项目。执行此操作时，请记住将第一个DropDownList的AutoPostBack属性设置为"true"。

基于其他DropDownList VB填充DropdownList

3 个答案: