Problem encoding PHP/MySQL arrays to JSON - php

Question

I have the following tables in MySQL:
recipe: id_recipe (PKey), name_recipe, description
url_pic: id_img, url_img, id_recipe (FKey)
Using PHP, I am trying to get JSON which contains every recipe, along with its pictures' urls (an array). My problem is that the pictures array of recipe 2 includes the pictures of both recipes! I'm a beginner and I can't find where the problem is. I've included below the JSON I want, my PHP code, and the JSON I actually get:
Desired JSON:
[
{
"recette": {
"id_recipe": "1",
"name_recipe": "..",
"description":"..."
},
"pictures": [
{
"id_url": "1",
"url": "picture 1 of recipe 1"
},
{
"id_url": "2",
"url": "picture 2 of recipe 1"
}
]
},
{
"recette": {
"id_recipe": "2",
"name_recipe": "....",
"description": "...."
},
"pictures": [
{
"id_url": "3",
"url": "picture 1 of recipe 2"
},
{
"id_url": "4",
"url": "picture 2 of recipe 2"
}
]
}
]
PHP:
$sql = "SELECT id_recipe,name_recipe,description
FROM recipe";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$data['recipe'] = $row;
$sql2= "SELECT id_url,url
FROM url_img as u
WHERE u.id_recipe = '$row[id_recipe]'";
$result2 = $conn->query($sql2);
if($result2->num_rows > 0){
while($row2 = $result2->fetch_array(MYSQL_ASSOC)) {
$array[] = $row2;
}
$data['pictures'] = $array;
}
$all[] = $data;
}
header('Content-Type: application/json');
echo json_encode($all,JSON_UNESCAPED_UNICODE);
}
Actual JSON:
[
{
"recette": {
"id_recipe": "1",
"name_recipe": "..",
"description":"..."
},
"pictures": [
{
"id_url": "1",
"url": "picture 1 of recipe 1"
},
{
"id_url": "2",
"url": "picture 2 of recipe 1"
}
]
},
{
"recette": {
"id_recipe": "2",
"name_recipe": "....",
"description": "...."
},
"pictures": [
{
"id_url": "1",
"url": "picture 1 of recipe 1"
},
{
"id_url": "2",
"url": "picture 2 of recipe 1"
},
{
"id_url": "3",
"url": "picture 1 of recipe 2"
},
{
"id_url": "4",
"url": "picture 2 of recipe 2"
}
]
}
]

Answer 1

Reset the array in each itteration
$result2 = $conn->query($sql2);
$array = []; // Add this line
if($result2->num_rows > 0){