请问老师出现这个问题是什么原因？

Question

Fatal error: Call to a member function select() on a non-object in F:\Work Space\Site\php\video\extend\Util\data\Sysdb.php on line 34

[1] ErrorException in Sysdb.php line 34

Call to a member function select() on a non-object

//这里

//返回一条记录 public function item(){

$item=Db::name($this->table)->field($this->field)->where($this->where)->find();

return $item ? $item : false ;

 }

//返回多条记录

public function lists(){

$query = Db::name($this->table)->field($this->field)->where($this->where)->select(); $this->order && $query = $query->order($this->order); $lists = $query->select(); return $lists ? $lists : false; } //自定义索引列表******************************************* public function cates($index){ $query = Db::name($this->table)->field($this->field)->where($this->where)->select(); $this->order && $query = $query->order($this->order); $lists = $query->select(); /*dump($lists); exit();*/

Answer 1

看第34行的select 有没有数据返回。