alert(eventArgs.get_value(））返回所选文本，而不是ID

我正在使用下面的代码用自动完成填充文本框，当选择时，它不会给我行ID，而是只给我选择的文本。alert（eventArgs.get_value（））没有返回SQL中行的实际ID的原因是什么？

<script language="javascript" type="text/javascript">
    function getSelected(source, eventArgs) {
        alert(eventArgs.get_value())
    }
</script>
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    AutoCompleteExtender.OnClientItemSelected = "getSelected"
End Sub
Public Function GetCompletionList(prefixText As String, count As Integer, ByVal contextKey As String) As String()
    Try
        Dim Con As SqlConnection
        Dim cmd As SqlCommand
        Con = New SqlConnection
        Dim test As String
        test = contextKey
        Con.ConnectionString = ""
        Con.Open()
        cmd = New SqlCommand
        cmd.Connection = Con
        'cmd.CommandText = "SELECT NPI, [Entity Type Code], [Provider Last Name (Legal Name)], [Provider First Name], [Provider Business Mailing Address City Name] FROM NPIData WHERE [Provider Last Name (Legal Name)] LIKE @Provider + '%' AND [Provider Business Mailing Address City Name] = @State"
        cmd.CommandText = "SELECT NPI, [Entity Type Code], [Provider Last Name (Legal Name)], [Provider First Name], [Provider Business Mailing Address City Name], [Provider Business Mailing Address State Name], [Provider Business Mailing Address Postal Code] FROM NPIData WHERE     ([Provider Business Mailing Address State Name] = @State) AND ([Provider Last Name (Legal Name)] LIKE N'%' + @Provider + N'%') ORDER BY [Provider First Name]"
        cmd.Parameters.AddWithValue("@Provider", prefixText)
        cmd.Parameters.AddWithValue("@State", contextKey)
        Dim customers As List(Of String) = New List(Of String)
        Dim reader As SqlDataReader = cmd.ExecuteReader()

        While reader.Read
            customers.Add(reader("Provider Last Name (Legal Name)").ToString + ", " + reader("Provider First Name").ToString + "          " + reader("Provider Business Mailing Address City Name").ToString + ", " + reader("Provider Business Mailing Address State Name").ToString + "  " + reader("Provider Business Mailing Address Postal Code").ToString)
        End While

        Con.Close()
        Return customers.ToArray
    Catch ex As Exception
    End Try