如何获取自定义下拉框选项改变事件
后台加载事件中调用‘创建填充属性值的控件’
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
  CreateAttrValueList()
End Sub
‘创建填充属性值的控件’代码如下：
Public Sub CreateAttrValueList()
  Dim dr As DataRowCollection = GetAttrName(PID)'获取商品属性名
  Dim ids As String = ""

  Dim i As Integer
  For i = 0 To dr.Count - 1

  Dim ddlAttr As DropDownList = New DropDownList()
  ddlAttr.ID = "ddl" & dr(i)("ID")

  ids += ddlAttr.ID & "," '拼接id集合

  Dim dr2 As DataRowCollection =GetAttrValue(PID，dr(i)("ID"))'获取商品属性值
  Dim j As Integer
  For j = 0 To dr2.Count - 1

  ddlAttr.Items.Add(New ListItem(dr2(j)("AttrValueCn"), dr2(j)("ID")))
  Next

  Me.plAttrList.Controls.Add(attrName)
  Me.plAttrList.Controls.Add(ddlAttr)

  Next
End Sub

以上功能效果已实现，现在我想在改变任意一个下拉框时，根据下拉框的值查询信息。
各位大虾，怎么获取这种自动创建下拉框的选项改变事件？或者还有没有其它解决方案，麻烦贴出来。先谢啦！~

------解决方案--------------------
ddlAttr.AutoPostBack = True

AddHandler ddlAttr.SelectedIndexChanged, AddressOf OnSelectedIndexChanged





Protected Sub OnSelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)

Dim ddl As DropDownList = DirectCast(sender, DropDownList)

Dim ID As String = ddl.ID

 

'Place the functionality here

ClientScript.RegisterClientScriptBlock(Me.GetType(), _

"Alert", "<script type = 'text/javascript'>alert('" & ID _

& " fired SelectedIndexChanged event');</script>")

End Sub