JavaScript - Auto Populate Based On Dropdown, Help

SELECT * FROM Cars
ORDER BY date modified

var xMonths = new Array( '01', '02', '03', '04', '05', '06', '07', '08', '09', '10', '11', '12' );

function getListValue( option_object  ){return option_object[ option_object.selectedIndex ].value;}
function setListValue( option_object, value  ){ option_object.selectedIndex = value;}
function addDays(myDate,days) {
    return new Date(myDate.getTime() + days*24*60*60*1000);
}
function init()
{
xToday = new Date();
yToday = addDays(new Date(),3);

xMonth = xToday.getMonth();
xDay = xToday.getDate()-1;
xYear = xToday.getYear()-2005; if (xYear < 2005) xYear=0;
yMonth = yToday.getMonth();
yDay = yToday.getDate()-1;
yYear = yToday.getYear()-2005; if (yYear < 2005) yYear=0;
  xF = document.forms['quickbooking'];
  setListValue( xF.ETAHour, 9 )
  setListValue( xF.ETAMonth, xMonth )
  setListValue( xF.ETADay, xDay )
  setListValue( xF.ETAYear, xYear )
  setListValue( xF.ETTHour, 9 )
  setListValue( xF.ETTMonth, yMonth )
  setListValue( xF.ETTDay, yDay )
  setListValue( xF.ETTYear, yYear )
}

<select class="formField" name="ETAMonth">
                <option value="<? echo $monthid; ?>"  selected="selected"><? echo $month; ?></option>
                <option 
                                value="01">January</option>
                <option 
                                value="02">February</option>
                <option value="03">March</option>
                <option 
                                value="04">April</option>
                <option value="05">May</option>
                <option 
                                value="06">June</option>
                <option value="07">July</option>
                <option 
                                value="08">August</option>
                <option value="09">September</option>
                <option 
                                value="10">October</option>
                <option value="11">November</option>
                <option 
                                value="12">December</option>
              </select>
              <select 
                                class="formField" name="ETAYear">
              <option value="<? echo $year; ?>" selected="selected"><? echo $year; ?></option>
              <option value="2008">2008</option>
              <option value="2009">2009</option>
              <option value="2010">2010</option>
            </select>

<option value="100">Product 1</option>
<option value="150">Product 2</option>
<option value="200">Product 3</option>

In October, the dropdown will display these prices
<option value="50">Product 1</option>
<option value="100">Product 2</option>
<option value="150">Product 3</option>

<script language="JavaScript" type="text/javascript">
<!--

/*
*** Multiple dynamic combo boxes
*** by Mirko Elviro, 9 Mar 2005
*** Script featured and available on JavaScript Kit (http://www.javascriptkit.com)
***
***Please do not remove this comment
*/

// This script supports an unlimited number of linked combo boxed
// Their id must be "combo_0", "combo_1", "combo_2" etc.
// Here you have to put the data that will fill the combo boxes
// ie. data_2_1 will be the first option in the second combo box
// when the first combo box has the second option selected


// first combo box

	data_1 = new Option("1", "$");
	data_2 = new Option("2", "$$");

// second combo box

	data_1_1 = new Option("11", "-");
	data_1_2 = new Option("12", "-");
	data_2_1 = new Option("21", "--");
	data_2_2 = new Option("22", "--");
	data_2_3 = new Option("23", "--");
	data_2_4 = new Option("24", "--");
	data_2_5 = new Option("25", "--");

// third combo box

	data_1_1_1 = new Option("111", "*");
	data_1_1_2 = new Option("112", "*");
	data_1_1_3 = new Option("113", "*");
	data_1_2_1 = new Option("121", "*");
	data_1_2_2 = new Option("122", "*");
	data_1_2_3 = new Option("123", "*");
	data_1_2_4 = new Option("124", "*");
	data_2_1_1 = new Option("211", "**");
	data_2_1_2 = new Option("212", "**");
	data_2_2_1 = new Option("221", "**");
	data_2_2_2 = new Option("222", "**");
	data_2_3_1 = new Option("231", "***");
	data_2_3_2 = new Option("232", "***");

// fourth combo box

	data_2_2_1_1 = new Option("2211","%")
	data_2_2_1_2 = new Option("2212","%%")

// other parameters

    displaywhenempty=""
    valuewhenempty=-1

    displaywhennotempty="-select-"
    valuewhennotempty=0


function change(currentbox) {
	numb = currentbox.id.split("_");
	currentbox = numb[1];

    i=parseInt(currentbox)+1

// I empty all combo boxes following the current one

    while ((eval("typeof(document.getElementById(\"combo_"+i+"\"))!='undefined'")) &&
           (document.getElementById("combo_"+i)!=null)) {
         son = document.getElementById("combo_"+i);
	     // I empty all options except the first one (it isn't allowed)
	     for (m=son.options.length-1;m>0;m--) son.options[m]=null;
	     // I reset the first option
	     son.options[0]=new Option(displaywhenempty,valuewhenempty)
	     i=i+1
    }


// now I create the string with the "base" name ("stringa"), ie. "data_1_0"
// to which I'll add _0,_1,_2,_3 etc to obtain the name of the combo box to fill

    stringa='data'
    i=0
    while ((eval("typeof(document.getElementById(\"combo_"+i+"\"))!='undefined'")) &&
           (document.getElementById("combo_"+i)!=null)) {
           eval("stringa=stringa+'_'+document.getElementById(\"combo_"+i+"\").selectedIndex")
           if (i==currentbox) break;
           i=i+1
    }


// filling the "son" combo (if exists)

    following=parseInt(currentbox)+1

    if ((eval("typeof(document.getElementById(\"combo_"+following+"\"))!='undefined'")) &&
       (document.getElementById("combo_"+following)!=null)) {
       son = document.getElementById("combo_"+following);
       stringa=stringa+"_"
       i=0
       while ((eval("typeof("+stringa+i+")!='undefined'")) || (i==0)) {

       // if there are no options, I empty the first option of the "son" combo
	   // otherwise I put "-select-" in it

	   	  if ((i==0) && eval("typeof("+stringa+"0)=='undefined'"))
	   	      if (eval("typeof("+stringa+"1)=='undefined'"))
	   	         eval("son.options[0]=new Option(displaywhenempty,valuewhenempty)")
	   	      else
	             eval("son.options[0]=new Option(displaywhennotempty,valuewhennotempty)")
	      else
              eval("son.options["+i+"]=new Option("+stringa+i+".text,"+stringa+i+".value)")
	      i=i+1
	   }
       //son.focus()
       i=1
       combostatus=''
       cstatus=stringa.split("_")
       while (cstatus[i]!=null) {
          combostatus=combostatus+cstatus[i]
          i=i+1
          }
       return combostatus;
    }
}

//-->
</script>

<form>
<select name="combo0" id="combo_0" onChange="change(this);" style="width:200px;">
	<option value="value1">-select-</option>
	<option value="value2">1</option>
	<option value="value3">2</option>

</select>
<BR><BR>
<select name="combo1" id="combo_1" onChange="change(this)" style="width:200px;">
	<option value="value1">  </option>
</select>
<BR><BR>
<select name="combo2" id="combo_2" onChange="change(this);" style="width:200px;">
	<option value="value1">  </option>
</select>
<BR><BR>
<select name="combo3" id="combo_3" onChange="change(this);" style="width:200px;">
	<option value="value1">  </option>

</select>

</form>

<p align="center">This free script provided by<br />
<a href="http://javascriptkit.com">JavaScript
Kit</a></p>

<html>
<head>
</head>
<body>

<form name="people">
<select name="group">
 
 
<option value="Pick Your Name">Choose</option>
<option value="Tom">Tom</option>
<option value="Freddy">Freddy</option>
<option value="Todd">Todd</option>
<option value="Fred">Fred</option>
<option value="William">William</option>
<option value="Johnson">Johnson</option>
</select>
<INPUT TYPE=submit VALUE="submit"> 
</form>
</body>
</html>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
 
<head>

<title>HTML Template</title>
 
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name="description" content="" />
<meta name="keywords" content="" />

<script type="text/javascript">
//<![CDATA[

function store(element) {

// store values

	var cl = element;
	
	var text_list = new Array();
			
	var value_list = new Array();
	
	var length = cl.length;
	
	for (var foo=0; foo<length; foo++) {
	
		text_list[foo] = cl.options[foo].text;
		
		value_list[foo] = cl.options[foo].value;
		
		alert("text array " + foo + " " + text_list[foo]);
		
		alert("value array " + foo + " " + value_list[foo]);
		
	}
	
	populate(cl, text_list, value_list);

}

function populate(element, text, value) {

	// populate options with previously stored values
	
	var cl = element;
	
	var length = cl.length;

	cl.options.length=0;	
	
	for (var bar=0; bar<length; bar++) {
		
		cl.options[bar]= new Option(text[bar], value[bar], false, false);
		
	}
	
}

function crafty_set_country(code) {	

	var cl = document.getElementById('select');
	
	store(cl);
	
	for (var i=0; i<cl.length; i++) {

		if (cl.options[i].value == code) {

			alert(cl.options[i].value + " found");
			
			var value = cl.options[i].value;
			
			var text = cl.options[i].text;
			
			cl.options.length=0;
			
			cl.options[0]=new Option(text, value, true, true);
			
			/*
			for (var j=0; j<cl.length; j++) {
			
				alert("second loop " + cl.options[j].text);
				
				if (cl.options[i].value != code) {
				
					cl.options[j]
				
				}
			
			}
			*/
			
		} else {
		
		alert(cl.options[i].value);
		
		}
		
	}
	
}

//]]>
</script>

</head>
 
<body>

<form>

<select id="select">
  <option value="10">ten</option>
  <option value="20">twenty</option>
  <option value="30">thirty</option>
  <option value="40">fourty</option>
  <option value="50">fifty</option>
  <option value="60">sixty</option>
</select>

<input type="button" value="remove" name="button" onClick="crafty_set_country(50)">
<input type="button" value="repopulate" name="button" onClick="crafty_set_country(100)">

</form>

</body>
</html>