How can I get no data?

Question

 /***

* Get username

*/

 public function left(){

$admin_id = session('admin_id');

$user_name=M("admin");

$user_name=$user_name->where($admin_id )->find();

$this->assign('user_name',$user_name);

$this->display();

}

用户名：<td>{$user_name}</td>

Answer 1

Where should give the query field, such as where('id',$admin_id)

Answer 2

First, check whether your $user_name has got a value; then check

Answer 3

Is the where syntax wrong?