PHP/MySQL多维数组

我是多维数组的新手，遇到了一个问题，无法集中精力解决它。我一直在努力扭转这一局面：

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 ) ) )

---

我已经有一段时间没有使用PHP了，这可能不起作用

更好的方法是检查是否至少存在一个艺术家子阵列，而不是

$isSet

标志

$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']);
  }
}

这是另一种方法（也可能不起作用）

---

第一个数组应该在循环外，第二个数组应该在循环内。使

$isSet=false

外部循环，然后内部循环添加

如果（！$isSet）{firstArray…；$isSet=TRUE；}否则{secondArray…；}

您不应该在同一数组中使用具有不同值的相同数组键（artist_id，lastName）。感谢有关isSet的提示。这对我很有用：

foreach（$stmt->fetchAll（PDO:：FETCH_ASSOC）as$r）{$artist[]=array（'artist_id'=>$r['artist_id']，'lastName'=>$r['lastName']）；}$stmt->execute；foreach（$stmt->fetchAll（PDO:：FETCH_ASSOC）as$r）{if（！isset（$category））{$category[]=array（'cat_id'=>r['cat_id']，'cat_description'=>r['cat_description']，'artists'=>$artist）；}

$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']);
}

$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']);
  }
}

$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']);
  }
}