JSON from SQL Table get double result - php

Question

first of all i have to tell you that it is my first step on php and JSON.
I decided to use JSON to get value from a customer SQL Table.
I get my results using this script :
mysql_connect($config['mysql_host'],$config['mysql_user'],$config['mysql_pass']);
//select database
#mysql_select_db($config['db_name']) or die( "Unable to select database");
mysql_query('SET CHARACTER SET utf8');
$fet=mysql_query('select * from vehicule');
$json = array();
while($r=mysql_fetch_array($fet)){
$json[] = $r;
}
header('Content-Type: application/json');
echo $json_data=json_encode($json);
Everything is ok, exept that my JSON results looks like :
0 = 462;
1 = "Hyundai ix20 crdi 115 panoramic sunsation";
10 = 1346450400;
11 = "462-Hyundai-ix20-crdi-115-panoramic-sunsation";
12 = 462;
...
id = 462;
kilometrage = 14400;
marque = 4;
modele = 137;
motorisation = 2;
ordre = 462;
prix = 17500;
puissance = 6;
titre = "Hyundai ix20 crdi 115 panoramic sunsation";
url = "462-Hyundai-ix20-crdi-115-panoramic-sunsation";
...
I have result of the table in 2 versions : one with 0:value, 1:value, 2... and the other one using the table key, how can i print only the second one ?
By the way can someone give me link so i can know by what i have to replace mysql which is think out of date ? (i'm a beginner few hours using PHP)
Thank you very much !

Answer 1

You have two different issues happening here. One is outright causing the issue you are seeing, and the other is a bad practice mistake that will leave you wide open for trouble in the long run.
The first issue is the one you're asking about. The mysql_fetch_array function (see the Docs here) expects a minimum of one input (the result input) that you are providing. It also has a second, optional input. That optional input defaults to MYSQL_BOTH, which returns an associative array with the results available both through keys (column names) and their indexes. Which is to say, that if you select the column 'id', you get it's value in both $array[0] and $array['id']. It's duplicated, and thus the JSON process carries over the duplication. You need to provide a second value to the function, either MYSQL_ASSOC to get $array['id'] or MYSQL_NUM to get $array[0].
Your second issue is the choice of functions. You're using the 'raw' mysql functions. These have been depreciated, which is a technical term that means 'these functions are no longer supported, but we've left them in to give you time to fix legacy code'. For legacy, read 'old'. Those functions will be going away soon, and you need to upgrade to a better option -- either the mysqli functions, or the PDO class. I strongly recommend the PDO class, as once you learn it it's easy to learn and has the advantage of being more portable. Whichever set you go with, you need to learn to use prepared statements as both a performance and security issue. Right at the moment, you're working with 'raw' statements which have a history of being very easy to interfere with via what's called an 'injection attack'. You can see a fictionalized example of such an attack here, and there are plenty of articles online about it. These attacks can be incredibly complex and difficult to fight, so using prepared statements (which handle it for you), is strongly recommended. In the specific example you're using here, you don't need to worry about it because you aren't including any user inputs, but it's an important habit to get into.