fastadmin 一对一和一对多关联模型查询

### 关联写入(新增)
```php
$this->model->stuscore()->save(["score"=>111,"student_id"=>$this->model->id]);
$this->model->studentmoney()->save(["money"=>12,"student_id"=>$this->model->id]);
```

### 关联修改
```php

$row->stuscore->score="xx";
$row->studentmoney->money="xxx";
$row->together(['stuscore','studentmoney'])->save();
关联删除
$v->together(['stuscore','studentmoney'])->delete();
// 或者
$v->stuscore()->delete();
$v->studentmoney()->delete();
```

### 一对多
```php
hasMany('关联模型名','本表外键名','本表主键名',['模型别名定义']);
```

### 关联统计
withCount()
也可在前端做统计

```php
$this->model->withCount('score')->where($where)->select();
```

### 关联查询
貌似是tp5.0的问题，没找到更好的办法
```php

$total = $this->model
  ->alias('student')
          ->with(['stuclass','stuscore'])
          ->join('stuscore','stuscore.student_id = student.id','LEFT')
        
          ->where($where)
          ->group('student.id')
          ->count();
  
 
  $list = $this->model
  ->alias('student')
          ->with(['stuclass','stuscore'])
          ->join('stuscore','stuscore.student_id = student.id','LEFT')
          ->distinct(true)
          ->where($where)
          ->order($sort, $order)
          ->limit($offset, $limit)
          // ->fetchSql(true)                    
          ->select();
```

注意with和join同时用可能会有问题，可以改写为alisa join写法
```php

$total = $this->model
        ->alias('student')
        ->join('stuscore','stuscore.student_id = student.id','left')
        ->join('studentmoney','studentmoney.student_id = student.id','left')
    
        ->field('student.*')
        ->where($where)
        ->group('student.id')
        ->count();
 
$list = $this->model
->alias('student')
->join('stuscore','stuscore.student_id = student.id','left')
->join('studentmoney','studentmoney.student_id = student.id','left')
 
->field('student.*')
->where($where)
->order($sort, $order)
->limit($offset, $limit)
->select();
 
foreach ($list as $row) {
    $row->stuscore = model('stuscore')->where('student_id',$row->id)->select();
    $row->studentmoney = model('studentmoney')->where('student_id',$row->id)->select();
}
```

### 关联新增
```php
$this->model->stuscore()->saveAll([
  ["score"=>111,"student_id"=>$this->model->id],
  ["score"=>333,"student_id"=>$this->model->id]
]);
```

### 关联修改
感觉没有这个场景吧，together()貌似不支持，我也不会~
如果真要批量改的话，就这样吧：

```php
$this->model->stuscore()->where('student_id',$ids)->update(["score"=>"888"]);
```

### 关联删除
```php
foreach ($list as $k => $v) {
  $count += $v->delete();
  $v->stuscore()->delete();
}
```