计算 Laravel 中两列之间的差异之和

Question

我正在尝试计算“缺勤”表中“从”和“到”列之间的差异总和，但遇到错误。

未找到列：1054 未知列“absences.hours_difference” ‘字段列表’

$classesAbsences = Classes::withSum([
    'absences' => function ($query) {
        $query->selectRaw('TIMESTAMPDIFF(HOUR, `from`, `to`) AS hours_difference');
    }
], 'absences.hours_difference')
    ->get();

Answer 1

您可以使用

with

方法加载

absences

关系，然后手动计算总和。

$classesAbsences = Classes::with([
    'absences' => function ($query) {
        $query->selectRaw('TIMESTAMPDIFF(HOUR, `from`, `to`) AS hours_difference');
    }
])->get();

// Calculate the sum manually
$classesAbsences->each(function ($class) {
    $class->total_hours_absence = $class->absences->sum('hours_difference');
});