//获取学生信息
private function ground($data)
{
$stu = array(); //新建一个学号栈，存储学生学号
foreach($data as $key=>$value)
{
if(in_array($value["studentid"],$stu)) //判断学号是不是已经被存储
{
array_push($array[$value["studentid"]],$value["selectbh"]); //入栈
array_push($array[$value["studentid"]],$value["taskid"]); //入栈
}
else
{ // 动态新建学生信息栈。
$array[$value["studentid"]] = array($value['selectbh'],$value['taskid']);
array_push($stu,$value["studentid"]); //再学号栈里面没有的学号入栈
}
}
unset($stu); //注销学号栈
return $array; //返回学生信息节点
}

array(2) {
 ["10408400227"] => array(4) {
  [0] => string(1) "1"
  [1] => string(1) "4"
  [2] => string(1) "2"
  [3] => string(1) "5"
 }
 ["10408400229"] => array(6) {
  [0] => string(1) "1"
  [1] => string(1) "4"
  [2] => string(1) "2"
  [3] => string(2) "28"
  [4] => string(1) "3"
  [5] => string(2) "14"
 }
}