php报错 Call to a member function bindColumn() on boolean in

错误提示 Fatal error: Call to a member function bindColumn() on boolean in

问题相关代码

qy表只有三个字段，qyname，qyid，mid

function getqy($qyid,$dblj){
    $qy = new mqy();
    $sql = "select * from `qy` WHERE qyid=$qyid";
    $cxjg = $dblj->query($sql);
    $cxjg->bindColumn('qyname',$qy->qyname);
    $cxjg->bindColumn('qyid',$qy->qyid);
    $cxjg->bindColumn('mid',$qy->mid);
    $cxjg->fetch(\PDO::FETCH_ASSOC);
    return $qy;
}

我尝试修改如下，依然报错

   $cxjg->bindColumn(1,$qy->qyname);
    $cxjg->bindColumn(2,$qy->qyid);
    $cxjg->bindColumn(3,$qy->mid);

很明显就是方法没有找到，你看下这个$dblj->query($sql);返回的对象看是否包含方法bindColumn