Laravel where date / Carbon 相關操作

//找出日期年份是2021年的

->whereYear('datetime', 2021)

//找出日期月份是7月的

->whereMonth('datetime', 7)

->whereDate('datetime', '<=', (new Carbon("2021-7"))->subMonth(1))

需特別注意，subMonth(x)會改變原來的值，比如以下範例，假如$today是2021/09/24，減掉6個月後$today的值會被更動:

$today = Carbon::today();
$today->subMonth(6)  //這時$today=2021/03/24

如果後面繼續$today->subMonth(x)，$today會越來越小，這種狀況可以用->toImmutable()來解決，這樣$today就不會變了:

->whereDate('create_datetime', '>=', $today->toImmutable()->subMonth(6))
->whereDate('create_datetime', '>=', $today->toImmutable()->subMonth(1))

//column between two date

->whereBetween('data_create_datetime', 
[(new Carbon($start_date))->startOfDay(), 
(new Carbon($end_date))->endOfDay()]);

$start_date = 2021/10/13
$end_date = 2021/10/20
(new Carbon($start_date))->startOfDay()   // => 2021/10/13 00:00:00
(new Carbon($end_date))->endOfDay()      // => 2021/10/20 23:59:59

//date between two columns

->whereDate('start_datetime', '<=', $date)->whereDate('end_datetime', '>=', $date)

//日期format轉換

Carbon::parse("2021/11/28")->format('Y-m-d');   //2021-11-28

//減1小時

Carbon::parse("2021-12-03 16:00:00")->subHour(1);  //2021-12-03 15:00:00

//現在時間與指定時間差了幾分鐘

$diff_in_minutes = (Carbon::now())->diffInMinutes('09:00:00', false);

帶入false表示回傳的相減分差會有正負數，如果帶true，則都會是正數。

本筆記參考:
1. https://stackoverflow.com/questions/34413877/php-carbon-class-changing-my-original-variable-value
2. https://www.pakainfo.com/laravel-where-date-between-multiple-columns/