ThinkPHP下Sql搜索'or'组合语法

$map['is_neibu'] = 0;
$twhere['username']  = array('like', '%'.$nickname.'%');
$twhere['nickname']  = array('like','%'.$nickname.'%');
$twhere['_logic'] ='or';
$map['_complex'] = $twhere;   //or条件完成
$count = $member->where($map)->count();