trying to run a query using php curl session and adding for loop inside php
===

There is an ajax request from javascript file which passes two values to the php file..
The php file should run the query using curl session, the way Ive tried to work this out is this way..

    var queryData={"data":{"data_string":{"data":"oil","default_field":"Content"}}};
    var testArgument=0;
 
    $.ajax({
	url:"/www/test/php/queryManipulate.php",
	type: 'POST',
	data: 'dataString',
	datatype: 'json',
	data: {field : queryData, start : testArgument},
	success:function(jsonQuery)
	{
		alert(jsonQuery);
	}
	});

Now what I am trying to do with php file is that, the I wanna add the value of "from" in to the query part, so that it looks like 
{"from": value of testArgument, "data":{"data_string":{"data":"oil","default_field":"Content"}}}

and the testArgument should have 4 values, 0,10,20,30 and each value should run the request.
My php file looks like 

    <?php
    $ch = curl_init();
    $from=$_POST["start"];
    $object=json_decode($_POST["field"]); 
    $object->from=$_POST["start"]; 
    curl_exec($ch);
    curl_close($ch);
    ?>

Im nt sure if I am using the curl right way.. Getting the error "Call to undefined function curl_init()"