passing null querystringparam

Version 1
    This document was generated from CDN thread

    Created by: Cindy Brozyno on 01-02-2012 07:51:50 AM
    I'm building a service that will pass a UserID (qsp) from one page to the next.  The UserID is queried on the next page by sql.  If someone accidentally hits submit without entering any information, the phone displays an html error.  My solution at this point is to utilize a default value of 'space'; however, this is not a recommended solution.
    Placing 0 as a default value would solve the query issue; however, I cannot have default values visible on the screen.
    Is there any way to pass a null value?
    Any help is appreciated.  Thank you.
    function InputMenu()
        //Phone menu. Gets User ID (input) and forwards to next page.
        Response.Write("<Title>IP Time Clock</Title><Prompt>Enter UserID to Clock In</Prompt>\r\n");
        Response.Write("<DisplayName>User ID</DisplayName>\r\n");
        Response.Write("<DefaultValue> </DefaultValue>\r\n");
    Next Page code snippet - to give you an idea of how the value above is being used
    var SERVICE_DIR="CiscoIPServices";
        var serverIP = Request.ServerVariables("LOCAL_ADDR");
        var input = Request.QueryString("input");
        var sql;
        var Conn = Server.CreateObject("ADODB.Connection");
        var RS = Server.CreateObject("ADODB.Recordset");
        var RS = Server.CreateObject("ADODB.Recordset");
        sql=("SELECT * FROM dbo.vw_User_PinList WHERE PERSON_ID =("+input+") "); 
        RS.Open(sql, Conn);

    Subject: RE: passing null querystringparam
    Replied by: David Staudt on 10-02-2012 05:33:15 PM
    Can you not just leave the default value empty?  The URL request will have either '?input=' or be missing the input parameter entirely (depending on phone model), which you should be able to check for in your server side code:

    Subject: RE: passing null querystringparam
    Replied by: Cindy Brozyno on 18-02-2012 01:43:21 PM
    After reviewing the schema, I found that querystringparams minimum value = 1. So leaving an empty space will work, but cannot accept null.