think php sql () or ()

$map=array();
$condition=array();
     $condition['zt'] = 0;

          $condition['date'] = array('lt', $nowtime);;

          $condition['_logic'] = "and";

          $map['zt']=1;

          $map['date_hk']=array('lt', $nowtime);

          $map['_complex']=$condition;
          $map['_logic']='or';

where($map)