我写了一个多维数组，多次循环后的数组是3维的，求解如何装换维一维数组
public function fbcreate(){
$m=M('Reportall');
$dep=M('Dept_user');
$paper=M('Papers');
$num=$_POST['small'];
for ($i = 0; $i <count($num); $i++){
for ($j = 0; $j <count($num); $j++){
$data[$i]['username']=$_POST['small'][$i];
$condition[$i][$j]['busername']=$_POST['small'][$j];
$data[$i][$j]['userid']= $dep->where($condition[$i][$j])->getField("userid");
$data[$i][$j]['dept']= $_POST['dept'];
$data[$i][$j]['busername'] = $condition[$i][$j]['busername'];
$condition1['paperid']=$_POST['paperid'];
$data[$i][$j]['paperdes']=$paper->where($condition1)->getField("paperdes");
$data[$i][$j]['paperid']=$condition1['paperid'];
$data[$i][$j]['ksrq'] =$_POST['ksrq'];
$data[$i][$j]['jsrq'] =$_POST['jsrq'];
}
}
dump($data);
exit;