Laravel：使用自定义日期获取数据

Question

我想像这样在 laravel 中获取数据：

level: SMP
year: 2020
month: Jan - May
value : 46

level: SD
year: 2020
month: Feb-Apr
value : 23

其中“价值”是该月的学生人数。如何显示数据（尤其是月份部分）？我试过了，但它返回如下：

这是我的代码：

编辑：

例如，我想将同年同级别的数据合二为一， 之前：

level: SD
year: 2021
month: Jan
value : 2

level: SD
year: 2021
month: Feb
value : 1

level: SD
year: 2021
month: Mar
value : 4

level: SMP
year: 2020
month: Feb
value: 10

之后：

level: SD
year: 2021
month: Jan - Mar
value : 7

level: SMP
year: 2020
month: Feb
value: 10

Answer 1

这按级别分组并汇总月份： SQL：

$students = DB::table('students')->select(
    DB::raw("SUBSTRING_INDEX(grade,' ',-1) AS level"),
    DB::raw("DATE_FORMAT(students.created_at, '%Y') as year"),
    DB::raw('DATE_FORMAT(students.created_at, "%m") as month'),
    DB::raw('CAST(count(*) AS CHAR)as value')
)
    ->whereNotNull('grade')
    ->groupBy('level', 'year')
    ->orderBy('level','ASC')
    ->orderBy('year','ASC')
    ->get();
return $students;

/*$monthNum = function ($entry) {
  return Carbon\Carbon::parse('1 '.$entry->month)->month;
};*/

$students = $students->groupBy('level', 'year')->map(function($group, $level)/* use($monthNum)*/ {
  return (object)[
    "level" => $level,
    "year" => $group[0]->year,
    //"month" => date("M",mktime(0,0,0,$group->min($monthNum),1,date('Y')))." \u{2012} ".date("M",mktime(0,0,0,$group->max($monthNum),1,date('Y'))),
    "month" => date("M",mktime(0,0,0,$group->min(),1,date('Y')))." \u{2012} ".date("M",mktime(0,0,0,$group->max(),1,date('Y'))),
    "value"  => $group[0]->value
  ];
})->values();