Mysql Nested and declare as array - mysql

Question

I have 2 table that want to call in and make another array from it.
The first table is groups
| id | name | type |
1 premium pr
2 basic bs
The second table is sub-groups
| id | group_id | name |
1 1 forever
2 2 short
Actually I want to show the code like this. To have another array function declare as sub-groups
Array (
[id] => 1
[name] => Premium
[type] => pr
)[sub-groups] => Array (
[0] => Array (
[id] => 1
[group_id] => 1
[name] => forever))
I created this PDO sql connection
=================EDITED CODE====================
function getGroups(){
global $conn;
$stmt = $conn->prepare("SELECT * FROM groups");
$stmt->execute();
$stmt->setFetchMode(PDO::FETCH_ASSOC);
$groups = $stmt->fetchAll();
foreach($groups as $key => $val){
$stmt = $conn->prepare("SELECT * FROM sub_groups WHERE group_id = {$val['id']}");
$stmt->execute();
$stmt->setFetchMode(PDO::FETCH_ASSOC);
$program = $stmt->fetchAll();
foreach($program as $key => $val){
$groups['sub-groups'] = $program;
}
}
return $groups;
}
The code successfully show the groups Premium and Basic, But it's not showing the sub-groups inside the main groups. Did I miss something?
Anyone with help will be nice.

Answer 1

Array keys have to be unique. If you have two columns with the same name, only one of them can appear in the resulting associative array for the rows.
You need to assign an alias to at least one of the columns with the same name so it will show up differently in the results.
SELECT g.name as group_name, sg.group_id, sg.id AS subgroup_id, sg.name AS subgroup_name
FROM groups AS g
LEFT JOIN subgroups AS sg ON sg.group_id = g.id
When you're creating the PHP result, $groups['sub-groups'] needs to be an array. You're overwriting it with a single element each time through the loop.
<?php
function getGroups(){
global $conn;
$groups = [];
$stmt = $conn->prepare("
SELECT g.name as group_name, sg.group_id, sg.id AS subgroup_id, sg.name AS subgroup_name
FROM groups AS g
LEFT JOIN subgroups AS sg ON sg.group_id = g.id");
$stmt->execute();
$stmt->setFetchMode(PDO::FETCH_ASSOC);
while ($row = $stmt->fetch()){
if (!isset($groups[$row['group_name']])) {
$groups[$row['group_name']] = $row;
$groups[$row['group_name']]['sub-groups'] = [$row['subgroup_name']];
} else {
$groups[$row['group_name']]['sub-groups'][] = $row['subgroup_name'];
}
}
return $groups;
}