PHP/MySQL多維數組

Question

我是多維數組的新手，遇到了一個問題，無法繞過它。我一直在試圖把這樣的：

Array 
(
    [1] => Array 
     (
      [cat_id] => 1 
      [cat_name] => Schilderijen 
      [cat_description] => Omschrijving bij schilderijen 
      [artists] => Array 
       (
        [artist_id] => 1 
        [lastName] => ..some value 
       ) 

     ) 

) 
Array 
(
    [1] => Array 
     (
      [cat_id] => 1 
      [cat_name] => Schilderijen 
      [cat_description] => Omschrijving bij schilderijen 
      [artists] => Array 
       (
        [artist_id] => 4 
        [lastName] => ..some value 
       ) 

     ) 

) 

弄成這個樣子，所以我可以調用一個類別，並列出了相關的藝術家下方：

 
Array 
(
    [1] => Array 
     (
      [cat_id] => 1 
      [cat_name] => Schilderijen 
      [cat_description] => Omschrijving bij schilderijen 
      [artists] => Array 
       (
        [artist_id] => 1 
        [lastName] => ..some value 
        [artist_id] => 4 
        [lastName] => ..some value 
       ) 

     ) 

) 

我使用下面的代碼：

$cat_id = 1; 

$query = "SELECT * FROM `categorie_has_artists` "; 
$query .= " JOIN `categories` ON categories.cat_id = categorie_has_artists.cat_id AND categorie_has_artists.cat_id = :cat_id"; 
$query .= " JOIN `artists` ON artists.artist_id = categorie_has_artists.artist_id"; 

$stmt = $dbh->prepare($query); 
$stmt->bindParam(':cat_id', $cat_id, PDO::PARAM_INT); 
$stmt->execute(); 

while($row = $stmt->fetch(PDO::FETCH_ASSOC)){ 
    $array[$row['cat_id']] = array('cat_id' => $row['cat_id'], 'cat_name' => $row['cat_name'], 'cat_description' => $row['cat_description'], 'artist' => array()); 
    $array[$row['cat_id']]['artist'][] = array('artist_id'=>$row['artist_id'], 'lastName' => $row['lastName']); 
} 

Answer 1

我有一段時間沒有使用PHP，這可能無法正常工作。

更好的方式是，以檢查是否ATLEAST一個藝術家子陣列exists代替$isSet標誌

$cat_id = 1; 

$query = "SELECT * FROM `categorie_has_artists` "; 
$query .= " JOIN `categories` ON categories.cat_id = categorie_has_artists.cat_id AND categorie_has_artists.cat_id = :cat_id"; 
$query .= " JOIN `artists` ON artists.artist_id = categorie_has_artists.artist_id"; 

$stmt = $dbh->prepare($query); 
$stmt->bindParam(':cat_id', $cat_id, PDO::PARAM_INT); 
$stmt->execute(); 

$isSet = FALSE; 

while($row = $stmt->fetch(PDO::FETCH_ASSOC)){ 
    if(!$isSet) { 
    $array[$row['cat_id']] = array('cat_id' => $row['cat_id'], 'cat_name' => $row['cat_name'], 'cat_description' => $row['cat_description'], 'artist' => array()); 
    $isSet = TRUE; 
    } else { 
    $array[$row['cat_id']]['artist'][] = array('artist_id'=>$row['artist_id'], 'lastName' => $row['lastName']); 
    } 
} 

這是其他的方式來做到這一點（也可能無法正常工作）

$cat_id = 1; 

$query = "SELECT * FROM `categorie_has_artists` "; 
$query .= " JOIN `categories` ON categories.cat_id = categorie_has_artists.cat_id AND categorie_has_artists.cat_id = :cat_id"; 
$query .= " JOIN `artists` ON artists.artist_id = categorie_has_artists.artist_id"; 

$stmt = $dbh->prepare($query); 
$stmt->bindParam(':cat_id', $cat_id, PDO::PARAM_INT); 
$stmt->execute(); 

while($row = $stmt->fetch(PDO::FETCH_ASSOC)){ 
    if(!isset($array[$row['cat_id']][$row['cat_name']][$row['cat_description']])) { 
    $array[$row['cat_id']] = array('cat_id' => $row['cat_id'], 'cat_name' => $row['cat_name'], 'cat_description' => $row['cat_description'], 'artist' => array()); 
    } else { 
    $array[$row['cat_id']]['artist'][] = array('artist_id'=>$row['artist_id'], 'lastName' => $row['lastName']); 
    } 
}