我正在嘗試按 3 個字段 Delivery_date、van_no 和 drop_no 將結果分組到一個數組中，這是我到目前為止所擁有的：// Gets all orders and sorts by delivery date, van and drop number    $getorders = $conn->prepare("SELECT * FROM orders INNER JOIN customers ON orders.customer_id = customers.customer_id INNER JOIN addresses on orders.address_id = addresses.address_id ORDER BY delivery_date, van_no, drop_no");    $getorders->execute();    $result = $getorders->fetchAll(\PDO::FETCH_ASSOC);        var_dump($result);這給了我這樣的輸出：array (size=6)  0 =>     array (size=8)      'orders_id' => string '6' (length=1)      'customer_id' => string '1' (length=1)      'address_id' => string '1' (length=1)      'van_no' => string '1' (length=1)      'drop_no' => string '0' (length=1)      'delivery_date' => string '2020-08-25' (length=10)      'customer_name' => string 'One' (length=3)      'address_postcode' => string 'b1' (length=2)  1 =>     array (size=8)      'orders_id' => string '1' (length=1)      'customer_id' => string '1' (length=1)      'address_id' => string '1' (length=1)      'van_no' => string '1' (length=1)      'drop_no' => string '1' (length=1)      'delivery_date' => string '2020-08-25' (length=10)      'customer_name' => string 'One' (length=3)      'address_postcode' => string 'b1' (length=2)  2 =>     array (size=8)      'orders_id' => string '3' (length=1)      'customer_id' => string '2' (length=1)      'address_id' => string '2' (length=1)      'van_no' => string '1' (length=1)      'drop_no' => string '2' (length=1)      'delivery_date' => string '2020-08-25' (length=10)      'customer_name' => string 'Two' (length=3)      'address_postcode' => string 'b2' (length=2)如果我將其更改為 \PDO::FETCH_GROUP ，它似乎只是將每個數組的每個字段加倍，如果我在查詢中使用 GROUP BY ，它只會為每個字段提供一個結果。我試過了： foreach($data->delivery_date as $values) {      echo $values->van_no . "\n"; }但請注意：嘗試獲取非對象的屬性“delivery_date”，我嘗試編碼為 JSON，但陷入困境并嘗試分組?；旧衔椰F在完全迷失了，我在谷歌上搜索的有關 PDO 數組或 JSON 數組分組的所有內容最終都沒有執行任何操作或拋出如上所述的錯誤。