0

您好我想知道是否可以使用 Laravel 的 Eloquent 通过聚合函数（MAX、MIN、COUNT）对查询结果进行分组/排序。这些型号是：

class School extends Model{
   function students(){
       return $this -> hasMany(Student::class);
   }
}
class Student extends Model{
   function school(){
       return $this -> belongsTo(School::class);
   }
}

经典的一对多关系，我想执行下一个查询：

School::select('school.*', 'MAX(student.score) as best_score') -> join('student', 'student.school_id', '=', 'school.id') -> orderByDesc('best_score') -> toSql()

所以我想列出所有学生成绩最好的学校。Laravel Eloquent 呈现下一个查询：

select `school`.*, `MAX(student`.`score)` as `best_score` from `serije` inner join `student` on `student`.`school_id` = `school`.`id` order by `best_score` desc

所以他呈现MAX(student为一列并引发 sql 错误，有没有办法在不使用 collections的情况下绕过它，这个想法是充分利用 DB。

4

2 回答 2

1

您可以添加自定义属性，并在此自定义属性上执行 orderBy： 

class School extends Model
{
    public function students()
    {
       return $this->hasMany(Student::class);
    }

    public function getHighestScoreAttribute()
    {
        $student = $this->students()->orderBy('score')->first();

        return $student ? $student->score : 0; 
    }
}
class Student extends Model{
    public function school()
    {
       return $this->belongsTo(School::class);
    }
}

// Query
$schools = School::orderBy('highestScore')->all();
于 2018-10-15T19:56:10.787 回答
1

You can easily check this on School model .

public function students(){
   return $this->hasMany('App\Student','school_id','id')->orderByDesc('score');
}

Call this function on your controller with('students')

于 2018-10-15T21:23:40.647 回答