Question

I’m using for my android app a php file to communicate with the mySql DB i’m using. The php worked great when i just used the INSERT query, but when i added the SELECT query it just failed to return the JSON back to my app. The point is that after i add a row to the database i want to return the id of the new row. the id is int with auto-increment.

Here’s my PHP code:

<?php

/*
* Following code will create a new product row
* All product details are read from HTTP Post Request
*/

// array for JSON response
$response = array();

// check for required fields
if (isset($_POST['lat']) && isset($_POST['lon']) && isset($_POST['alt'])) {

$name = $_POST['lat'];
$price = $_POST['lon'];
$description = $_POST['alt'];

// include db connect class
require_once __DIR__ . '/db_connect.php';

// connecting to db
$db = new DB_CONNECT();

// mysql inserting a new row
$result = mysql_query("INSERT INTO sits(lat, lon, alt) VALUES($name, $price, $description)");

// check if row inserted or not
if ($result) {
    // successfully inserted into database
    $response["success"] = 1;
    $response["message"] = "sit created.";
    $result2 = mysql_query("SELECT id FROM sits ORDER BY id DESC LIMIT 1")
    while($row = mysql_fetch_array($result2))
    {
       $response["id"]=$row['id'];
    }
    // echoing JSON response
    echo json_encode($response);
} else {
    // failed to insert row
    $response["success"] = 0;
    $response["message"] = "Oops! An error occurred.";

    // echoing JSON response
    echo json_encode($response);
}
} else {
// required field is missing
$response["success"] = 0;
$response["message"] = "Required field(s) is missing";

// echoing JSON response
echo json_encode($response);
}
?>

Answer 1

You definitely need mysql_insert_id() for that. A SELECT query is unnecessary. The docs state:

Return Values

The ID generated for an AUTO_INCREMENT column by the previous query on
success, 0 if the previous query does not generate an AUTO_INCREMENT
value, or FALSE if no MySQL connection was established.

if ($result) {
    // successfully inserted into database
    $response["success"] = 1;
    $response["message"] = "sit created.";
    $response["id"] = mysql_insert_id();
    // echoing JSON response
    echo json_encode($response);
}