$dateTrunc (표현식 연산자)

binSize 및 unit 필드

Together, binSize and unit specify the time period used in the $dateTrunc calculation.

예를 들면 다음과 같습니다.

• If binSize is 1 and unit is hour, the time period is one hour. For the date 2021-03-20T11:30:05Z, $dateTrunc returns 2021-03-20T11:00:00Z.

• If binSize is 2 and unit is hour, the time period is two hours. For the date 2021-03-20T11:30:05Z, $dateTrunc returns 2021-03-20T10:00:00Z.

$dateTrunc:

• Divides the time for the $dateTrunc calculation into binSize time periods in the specified time unit.

  The time periods start at a reference date, which is determined by unit. If unit is:

  • A string other than week, $dateTrunc uses a reference date of 2000-01-01T00:00:00.00Z. For example, if binSize is 10 and unit is year, example time periods are:

    • 2000-01-01T00:00:00.00Z

    • 2010-01-01T00:00:00.00Z

    • 2020-01-01T00:00:00.00Z

  • Equal to week, $dateTrunc uses a reference date that is set to the earliest first day of the week that is greater than or equal to 2000-01-01. The first day is set using startOfWeek (the default is Sunday).

• Returns the lower boundary of the time period that the date is in. The boundary is returned as an ISODate. If the binSize field is 1, $dateTrunc sets the least significant parts (as determined by unit) of the returned ISODate to 0 and keeps the rest of the ISODate the same.

단위 가 다음과 같은 경우:

• year: $dateTrunc returns the ISODate for the start of January 1 for the year in date.

• quarter: $dateTrunc returns the ISODate for the start of the first day of the calendar quarter in date.

  분기는 다음과 같습니다.

  • 1월~3월

  • 4월~6월

  • 7월~9월

  • 10월~12월

• month: $dateTrunc returns the ISODate for the start of the first day of the month in date.

• week: $dateTrunc returns the ISODate for the start of the startOfWeek day in date. The default for startOfWeek is Sunday.

• day: $dateTrunc returns the ISODate for the start of the day in date.

• hour: $dateTrunc returns the ISODate for the start of the hour in date.

• minute: $dateTrunc returns the ISODate for the start of the minute in date.

• second: $dateTrunc returns the ISODate for start of the second in date.

unit 및 startOfWeek 필드

단위 가 다음과 같은 경우:

• week 이외의 문자열인startOfWeek는 무시됩니다.

• week과 동일하며 startOfWeek는 다음과 같습니다.

  • Specified: $dateTrunc uses startOfWeek as the first day of the week for the calculation.

  • Omitted: $dateTrunc uses Sunday as the start of the week for the calculation.

$project 파이프라인 단계에서 주문 날짜 잘라내기

This example uses $dateTrunc in a $project stage to truncate the cake sales orderDate values to two weeks:

db.cakeSales.aggregate( [
   {
      $project: {
         _id: 1,
         orderDate: 1,
         truncatedOrderDate: {
            $dateTrunc: {
               date: "$orderDate", unit: "week", binSize: 2,
               timezone: "America/Los_Angeles", startOfWeek: "Monday"
            }
         }
      }
   }
] )

예시:

• $project 출력에 _id, orderDate, truncatedOrderDate 필드가 포함됩니다.

• $dateTrunc truncates the orderDate field to a 2 binSize week unit time period in the America/Los_Angeles timezone with startOfWeek set to Monday.

이 예시 출력에서는 잘린 orderDate가 truncatedOrderDate 필드에 표시됩니다.

[
   {
      _id: 0,
      orderDate: ISODate("2020-05-18T14:10:30.000Z"),
      truncatedOrderDate: ISODate("2020-05-11T07:00:00.000Z")
   },
   {
      _id: 1,
      orderDate: ISODate("2021-03-20T11:30:05.000Z"),
      truncatedOrderDate: ISODate("2021-03-15T07:00:00.000Z")
   },
   {
      _id: 2,
      orderDate: ISODate("2021-01-11T06:31:15.000Z"),
      truncatedOrderDate: ISODate("2021-01-04T08:00:00.000Z")
   },
   {
      _id: 3,
      orderDate: ISODate("2020-02-08T13:13:23.000Z"),
      truncatedOrderDate: ISODate("2020-02-03T08:00:00.000Z")
   },
   {
      _id: 4,
      orderDate: ISODate("2019-05-18T16:09:01.000Z"),
      truncatedOrderDate: ISODate("2019-05-13T07:00:00.000Z")
   },
   {
      _id: 5,
      orderDate: ISODate("2019-01-08T06:12:03.000Z"),
      truncatedOrderDate: ISODate("2019-01-07T08:00:00.000Z")
   }
]

$group 파이프라인 단계에서 주문 날짜 잘라내기 및 수량 합계 가져오기

이 예시에서는 $dateTrunc $group orderDate quantity 단계에서를 사용하여 케이크 판매 값을 6개월로 자르고 값의 합계를 반환합니다.

db.cakeSales.aggregate( [
   {
      $group: {
         _id: {
            truncatedOrderDate: {
               $dateTrunc: {
                  date: "$orderDate", unit: "month", binSize: 6
               }
            }
         },
         sumQuantity: { $sum: "$quantity" }
      }
   }
] )

예시:

• $group 은(는) _id 필드를 truncatedOrderDate 필드로 설정하여 cakeSales 문서를 그룹화하고 $sum을 사용하여 각 그룹에 대한 quantity 값의 합계를 반환합니다.

• $dateTrunc truncates the orderDate field to a 6 binSize month unit time period.

이 예제의 출력에서는 잘린 orderDate이 truncatedOrderDate 필드에 표시되고 quantity 합계가 sumQuantity 필드에 표시됩니다.

[
   {
      _id: { truncatedOrderDate: ISODate("2020-01-01T00:00:00.000Z") },
      sumQuantity: 224
   },
   {
      _id: { truncatedOrderDate: ISODate("2021-01-01T00:00:00.000Z") },
      sumQuantity: 285
   },
   {
      _id: { truncatedOrderDate: ISODate("2019-01-01T00:00:00.000Z") },
      sumQuantity: 296
   }
]