laravel查询生成器：依赖于主要内容的联接

Question

I'm using luman and Database Query Builder to fetch full user info from database.

First, Please Take a lock at my database structure: I have a table called users and a series of other tables that are related to user groups (Ex: secretaries , patients , doctors and admins ) which stores additional information about the users.

Also To determine user access, I have a level column on user table which can have one of this value as enum: 'admin', 'doctor', 'secretary', 'patient' .

So, I want to get this information using one query by join and select .

My training code is something like this:

$userInfo = User::where("userID", $userID)
           ->limit(1)
           ->join('[GROUP_TABLE_NAME]', function ($join) {
                  $join->on('user.userID', '=', '[GROUP_TABLE_NAME]' .'.'.
                                         '[GROUP_NAME]' . 'ID');
            })
            ->get();

The GROUP_NAME comes from level column on user table and the GROUP_TABLE_NAME can be built based on the GROUP_NAME value(Ex: ['secretary' => 'secretaries' , 'patient' => 'patients' , ...] ).

Any idea to handle the join structure using laravel query builder?

Answer 1

First you should be aware of the fact that this code architecture is not convenient and not easy to understand for other developers.

SQL You can achieve your goal by using union and join .

Just convert this query for laravel builder or use it directly with DB::statement : select users.*, infos.info from users left join (( select secretaries.* from secretaries ) UNION (select doctors.* from doctors)) infos ON users.id = infos.user_id where users.id=? .

But

The easiest way to do it is to fetch info in two queries, both indexed and fast: user from users by primary key and then info by indexed field user_id in it. Create Doctorinfo , Admininfo models and correspondent migrations. So user class can be smth like this:

public function getInfo() {
    switch($this->level) {
        'doctor':
            return $this->doctorinfo;
         ...
    }
}

private function doctorinfo() {
    $this->hasOne('App\Doctorinfo');
}

Builder

You can use left join to join all sub tables as well. The following builder selects info column.

User::where("userID", $userID)->limit(1)
   ->leftJoin('patients', 'users.id', '=', 'patients.user_id')
   ->leftJoin('doctors', 'users.id', '=', 'doctors.user_id')
   ->leftJoin('admins', 'users.id', '=', 'admins.user_id')
   ->select('users.*', DB::raw('IF(users.level="admin", admins.info, (IF users.level="doctors", doctors.info, patients.info))'))