PHP SQL Join Query menggabungkan konten dalam Multi-Array

Anda bisa melakukan ini dengan kombinasi PHP dan MySQL. Ubah kueri Anda menjadi ini:

SELECT section_titel as t1, GROUP_CONCAT(sub_section_titel) as t2 
FROM sections LEFT JOIN sub_sections ON section_id = sId
GROUP BY t1
HAVING t2 IS NOT NULL

Ini akan memberi Anda tabel hasil seperti ini:

t1              t2
Section One     SubOne,SubTwo
Section Three   SubThree

(Jika Anda menginginkan hasil untuk Section Two , hapus HAVING t2 IS NOT NULL kondisi dari kueri)

Kemudian di PHP Anda (saya berasumsi mysqli dengan koneksi $conn )

$result = mysqli_query($conn, $sql) or die(mysqli_error($conn));
$out = array();
while ($row = mysqli_fetch_array($result)) {
   $out[] = array('t1' => $row['t1'], 't2' => explode(',', $row['t2']));
}
print_r($out);

Keluaran:

Array
(
    [0] => Array
        (
            [t1] => Section One
            [t2] => Array
                (
                    [0] => SubOne
                    [1] => SubTwo
                )    
        )

    [1] => Array
        (
            [t1] => Section Three
            [t2] => Array
                (
                    [0] => SubThree
                )
        )
)