PHP: 我怎样才能拥有一个具有相同键的数组?

PHP: How can I have an array with same keys?

我有 2 个数组 $projectsIds = [1,2]$usersIds = [1,2,3]

我已经将 foreach 循环命名为这样:

foreach($projectsIds as $projecID){
           foreach($userIds as $userID){
           $sync_array[$projecID] = array('user_id' => $userID);
            }
       }
dd($sync_array);

现在我得到这样的结果:

array:2 [  1 => array:1 [    "user_id" => 1  ]  
           2 => array:1 [    "user_id" => 1  ]
        ]

有可能得到这样的结果:

array:2 [  1 => array:1 [    "user_id" => 1  ]  
           1 => array:1 [    "user_id" => 2  ] 
           1 => array:1 [    "user_id" => 3  ]
           2 => array:1 [    "user_id" => 1  ]
           2 => array:1 [    "user_id" => 2  ]
           2 => array:1 [    "user_id" => 3  ]
        ]

您希望 array in PHP 具有相同密钥的两个或多个实例,这根本不可能!

键应被视为唯一实体