BUG:
Db::name('user AS a')->join('user_detail AS b', 'a.uid = b.uid', 'LEFT')->where('a.uid = 1')->find() ; // 这么写的时候会抛异常;
Db::name('user as a')->join('user_detail as b', 'a.uid = b.uid', 'LEFT')->where('a.uid = 1')->find() ; // 把 AS 改成小写,这么写的时候就能查询了;