Question

I am having a form written in php. In this form there is field named ‘State’ and the Options of this field are the names of the states.There is another field named ‘District’ whose Options are the names of the District. The Options of the these two fields are being fetched from the database. There are about 28 states and there are about 12 Districts for each state. Now what is want is that when someone selects the state, then all the Districts corresponding to that state automatically appear in the District field.

Answer 1

you could use an ajax call

on the select put onchange="changedist(this.value)"

and use the script function

function changedist(str)
{
if (str=="")
  {
  document.getElementById("dist").innerHTML="";
  return;
  }
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("dist").innerHTML=xmlhttp.responseText;
    }


  }

xmlhttp.open("GET","./dist.php?q="+str,true);
xmlhttp.send();
}

and call this values in your page
<div id="dist"> here will returns the distrctis of the file dist.php</div>

and dist.php

$q = $_GET[q];
$sql= "select * from dist where state = $q";


$query ....


echo ' <select name=dist>';
while ($result = mysql_fetch_array($query))

{
echo " <option value=$result[key]>$result[dist]</option>";

}

so this will returns to your form page on the state change