yii---左查询使用

看到一些做关联查询的示例，例如使用hasMany(一对多)，还是有一个hasOne(一对一)的，没有细看，下面是我看到的一个比较好用的一个：

$query = (new \yii\db\Query())
            ->select('a.id as id,title,create_time,modify_time,username,name')
            ->from('yii_article AS a')
            ->leftJoin('yii_user AS u','u.id = a.user_id')
            ->leftJoin('yii_category AS c','c.id = a.category_id')
            ->where(['c.name'=>'新闻分类'])
            ->limit(4)
            ->orderBy('id DESC')
            ->All();

或者是这样：

$command = Admin::find()->select('tbl_user.*,tbl_admin.*')->join('LEFT JOIN','tbl_user','tbl_user.admin_id = tbl_admin.id')->asArray()->all();

具体使用：

$list = (new \yii\db\Query())
            ->select('a.content,a.created_time,b.title')
            ->from('forum_thread_post AS a')
            ->leftJoin('forum_thread AS b','a.thread_id = b.id')
            ->where(['a.user_id'=>$this->getUserid()])
            ->all();