Sorting

Nice direction from @K?! and good point from @dickersonka — the robust pattern is to return one row per fixture with the home and visitor as columns, let the database order those two columns, then build your 2‑D array in PHP (or sort again in PHP if you need locale-aware ordering).

A reliable SQL pattern (self-join) that yields one row per match, ordered by home name then away name:

SELECT m.id AS match_id,
       th.name AS home_team,
       ta.name AS away_team,
       m.time
FROM `match` m
JOIN team_match thm ON thm.match_id = m.id AND thm.home = 1
JOIN team th ON th.id = thm.team_id
JOIN team_match tam ON tam.match_id = m.id AND tam.home = 0
JOIN team ta ON ta.id = tam.team_id
ORDER BY th.name COLLATE utf8mb4_general_ci, ta.name COLLATE utf8mb4_general_ci;

If you prefer to pivot in one pass (safer if flags are messy), use CASE + GROUP BY:

SELECT m.id AS match_id,
       MAX(CASE WHEN tm.home = 1 THEN t.name END) AS home_team,
       MAX(CASE WHEN tm.home = 0 THEN t.name END) AS away_team
FROM `match` m
JOIN team_match tm ON tm.match_id = m.id
JOIN team t ON t.id = tm.team_id
GROUP BY m.id
ORDER BY home_team, away_team;

Build the nested array in PHP and ensure keys are sorted:

$rows = $pdo->query($sql)->fetchAll(PDO::FETCH_ASSOC);
$matrix = [];
foreach ($rows as $r) {
    $matrix[$r['home_team']][$r['away_team']] = [
        'match_id' => $r['match_id'],
        'time'     => $r['time'],
    ];
}
ksort($matrix, SORT_NATURAL | SORT_FLAG_CASE);
foreach ($matrix as &$sub) { ksort($sub, SORT_NATURAL | SORT_FLAG_CASE); }
unset($sub);

Troubleshooting notes:

• Verify every match returns exactly two entries; use a quick GROUP BY on the link table to find anomalies.
• Use COLLATE in SQL or PHP's Intl Collator for locale/case-sensitive ordering.
• If scores or other fields aren't strictly numeric, keep them as strings in your output and only parse them where needed.