thinkphp联表查询实例
该实例实现的目的：文章数据表关联用户表数据，代码如下
$catealias['tid'] = ['in',$childIds];
$article_list = Db::name('article')->alias('a')->join('user u', 'u.id=a.uid')->where('a.open', 1)->where($catealias)->field('a.*,u.username')
->order('a.id desc')->paginate($this->site_config['c_list_main']);
