数组 相同键值合并问题

$data =  '[    {      "ClientId": 0,      "RoleId": 2    },    {      "ClientId": 1,      "RoleId": 1    },    {      "ClientId": 1,      "RoleId": 4    }  ]';$data = json_decode($data);

$data =  '[    {      "ClientId": 0,      "RoleId": [2]    },    {      "ClientId": 1,      "RoleId": [1,4]    }  ]';$data = json_decode($data);

$data = json_decode($data, true);$arr = array();foreach($data as $itm) {	$arr[$itm['ClientId']]['ClientId'] = $itm['ClientId'];	$arr[$itm['ClientId']]['RoleId'][] = $itm['RoleId'];}$arr = array_values($arr);