How to write JAVA CLASS and PHP API to post and read from an existing MySQL database

I'm working on an application which allows employees to Request time off that post and read from an existing MySQL database. But I'm having a little trouble figuring out what to fix in this entire section of codes(PHP, JAVA). Could any expert show me how this can be fixed please?

It's the error message I'm currently getting

D/Create Response(284): {"message":"Required field(s) is missing","success":0}

Request PHP API

<?php
// array for JSON response
$response = array();

// check for the fields
if (isset($_POST['title']) && isset($_POST['request_date']) && isset($_POST['reqEndDate']) && isset($_POST['reason']) && isset($_POST['requestor']) && isset($_POST['status']) && isset($_POST['submitDate']) && isset($_POST['explanation']) && isset($_POST['hours']) && isset($_POST['id'])) {

    $title = $_POST["request_title"];
    $date = $_POST["request_date"];
    $eDate = $_POST["reqEndDate"];
    $reason = $_POST["reason"];
    $requestor = $_POST["requestor"];
    $status = $_POST["status"]; 
    $dateSubmitted = $_POST["submitDate"];
    $explanation = $_POST["explanation"];
    $numhours = $_POST["hours"];
    $empid = $_POST['id'];


    // mysql inserting a new row
    $result = mysql_query("INSERT INTO requests(request_title, request_date, reqEndDate, reason, requestor, status, submitDate, explanation, hours, empid) 
                            VALUES('$title', '$date', '$eDate', '$reason', '$requestor', '$status', '$dateSubmitted', '$explanation', '$numhours', '$empid')");


} else {

    $response["success"] = 0;
    $response["message"] = "Required field(s) is missing";

    echo json_encode($response);
}
?>

Request JAVA CLASS

            // Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("request_title", title));
            params.add(new BasicNameValuePair("request_date", date));
            params.add(new BasicNameValuePair("reqEndDate", eDate));
            params.add(new BasicNameValuePair("hours", hours));
            params.add(new BasicNameValuePair("reason", reason));
            params.add(new BasicNameValuePair("explanation", explanation));

            // getting JSON Object
            // Note that create request url accepts POST method
            JSONObject json = jsonParser.makeHttpRequest(url_create_request,
                    "POST", params);

            // check log cat fro response
            Log.d("Create Response", json.toString());

            // check for success tag
            try {
                int success = json.getInt(TAG_SUCCESS);

                if (success == 1) {
                    // successfully created request
                    Intent i = new Intent(getApplicationContext(), AllRequestsActivity.class);
                    startActivity(i);

                    // closing this screen
                    finish();
                } else {
                    // failed to create request
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;
        }



    }
}