DropDownList绑定数据源???怪……:(

[mybilly2016]

我在UserControl里面的DropDownList是用下面的方法绑定的数据源，但只是第一次会成功插入一条"(请选择)"的项，而其他Postback就没有
If c.GetType().ToString()= "System.Web.UI." & _
"WebControls.DropDownList" Then
Dim dv As DataView = New DataView(dt)
dv.RowFilter = EMPLOYEEDATA.HR_CODETYPE_ID_FIELD & _
"='" & Idvalue & "'"
CType(c, System.Web.UI.WebControls.DropDownList) _
.DataSource = dv
CType(c, System.Web.UI.WebControls.DropDownList) _
.DataTextField = EMPLOYEEDATA.SHORTNAME_FIELD
CType(c, System.Web.UI.WebControls.DropDownList) _
.DataValueField = EMPLOYEEDATA.HR_CODE_ID_FIELD
c.DataBind()
If c.Items.Count>0 Then
c.Items.Add(New ListItem("(请选择)","-1"))
End If
End If

[SunLightIce]

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