Tarih aralığını aralık açıklamasına dönüştürme

Yakın tarihli bir projedeki bir gereklilik, bir kaynağın ne zaman tamamen tüketileceğini bildirmektir. Tükenme takvimi tarihinin yanı sıra, kalan süreyi "1 yıl, 3 ay sürecek" gibi İngilizce biçiminde göstermem istendi.

Yerleşik DATEDIFFişlev

Belirtilen başlangıç ​​tarihi ile bitiş tarihi arasında geçen belirtilen tarih bölümü sınırlarının sayısını ... döndürür.

Olduğu gibi kullanılırsa, bu yanıltıcı veya kafa karıştırıcı sonuçlar doğurabilir. Örneğin, YEAR aralığının kullanılması 1999-12-31 (YYYY-AA-GG) ve 2000-01-01 yıllarını bir yıl arayla gösterirken, sağduyu bu tarihlerin sadece 1 günle ayrıldığını söyler. Buna karşılık 1999-12-31 ve 2010-12-31 GÜN aralığını kullanmak 4.018 günle ayrılırken, çoğu insan "11 yıl" ı daha iyi bir tanım olarak görür.

Gün sayısından başlayarak ve ayları ve yıllarını oradan hesaplamak artık yıl ve ay büyüklüğü hatalarına eğilimli olacaktır.

Bunun çeşitli SQL lehçelerinde nasıl uygulanabileceğini merak etmeliyim? Örnek çıktı şunları içerir:

create table TestData(
    FromDate date not null,
    ToDate date not null,
    ExpectedResult varchar(100) not null); -- exact formatting is unimportant

insert TestData (FromDate, ToDate, ExpectedResult)
values ('1999-12-31', '1999-12-31', '0 days'),
       ('1999-12-31', '2000-01-01', '1 day'),
       ('2000-01-01', '2000-02-01', '1 month'),
       ('2000-02-01', '2000-03-01', '1 month'),              -- month length not important
       ('2000-01-28', '2000-02-29', '1 month, 1 day'),       -- leap years to be accounted for
       ('2000-01-01', '2000-12-31', '11 months, 30 days'),
       ('2000-02-28', '2000-03-01', '2 days'),
       ('2001-02-28', '2001-03-01', '1 day'),                -- not a leap year
       ('2000-01-01', '2001-01-01', '1 year'),
       ('2000-01-01', '2011-01-01', '11 years'),
       ('9999-12-30', '9999-12-31', '1 day'),                -- catch overflow in date calculations
       ('1900-01-01', '9999-12-31', '8099 years 11 months 30 days');  -- min(date) to max(date)

SQL Server 2008R2 kullanıyorum ama diğer lehçelerin bunu nasıl ele alacağını öğrenmek istiyorum.

Aşağıdaki çözüm SQL Server içindir. Yaklaşım benzer Serg en Sorgu kullandığı yalnızca DATEADD ve DATEDIFF fonksiyonlarda. Bununla birlikte, negatif aralıkları ( FromDate > ToDate ) hesaba katmaz ve toplam ay farkından yıllar ve aylar türetir:

WITH
  MonthDiff AS
  (
    SELECT
      t.FromDate,
      t.ToDate,
      t.ExpectedResult,
      Months = x.Months - CASE WHEN DAY(t.FromDate) > DAY(t.ToDate) THEN 1 ELSE 0 END
    FROM
      dbo.TestData AS t
      CROSS APPLY (SELECT DATEDIFF(MONTH, t.FromDate, t.ToDate)) AS x (Months)
  )
SELECT
  t.FromDate,
  t.ToDate,
  t.ExpectedResult,
  Result = ISNULL(NULLIF(ISNULL(x.Years  + CASE x.Years  WHEN '1' THEN ' year '  ELSE ' years '  END, '')
                       + ISNULL(x.Months + CASE x.Months WHEN '1' THEN ' month ' ELSE ' months ' END, '')
                       + ISNULL(x.Days   + CASE x.Days   WHEN '1' THEN ' day '   ELSE ' days '   END, ''), ''), '0 days')
FROM
  MonthDiff AS t
  CROSS APPLY
  (
    SELECT
      CAST(NULLIF(t.Months / 12, 0) AS varchar(10)),
      CAST(NULLIF(t.Months % 12, 0) AS varchar(10)),
      CAST(NULLIF(DATEDIFF(DAY, DATEADD(MONTH, t.Months, t.FromDate), t.ToDate), 0) AS varchar(10))
  ) AS x (Years, Months, Days)
;

Çıktı:

FromDate    ToDate      ExpectedResult                 Result
----------  ----------  -----------------------------  -----------------------------
1999-12-31  1999-12-31  0 days                         0 days
1999-12-31  2000-01-01  1 day                          1 day 
2000-01-01  2000-02-01  1 month                        1 month 
2000-02-01  2000-03-01  1 month                        1 month 
2000-01-28  2000-02-29  1 month, 1 day                 1 month 1 day 
2000-01-01  2000-12-31  11 months, 30 days             11 months 30 days 
2000-02-28  2000-03-01  2 days                         2 days 
2001-02-28  2001-03-01  1 day                          1 day 
2000-01-01  2001-01-01  1 year                         1 year 
2000-01-01  2011-01-01  11 years                       11 years 
9999-12-30  9999-12-31  1 day                          1 day 
1900-01-01  9999-12-31  8099 years 11 months 30 days   8099 years 11 months 30 days 

Bu yanıt, bir SQL Server (2005+) CLR işlevi kullanan bir uygulamayı gösterir.

-- Enable CLR (if necessary)
EXECUTE sys.sp_configure 
    @configname = 'clr enabled',
    @configvalue = 1;

RECONFIGURE;

Montaj ve fonksiyon

CREATE ASSEMBLY DBA
AUTHORIZATION dbo
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WITH PERMISSION_SET = SAFE;
GO
CREATE FUNCTION dbo.IntervalDescription
(
    @From date, 
    @To date
)
RETURNS nvarchar(100)
AS EXTERNAL NAME 
    DBA.UserDefinedFunctions.IntervalDescription;

kullanım

SELECT 
    TD.FromDate,
    TD.ToDate,
    TD.ExpectedResult, 
    IntervalDescription = dbo.IntervalDescription(TD.FromDate, TD.ToDate) 
FROM dbo.TestData AS TD;

Sonuç

Kaynak

_{Ben bir C # programcısı değilim!}

using Microsoft.SqlServer.Server;
using System;
using System.Text;

public partial class UserDefinedFunctions
{
    [SqlFunction
        (
        DataAccess = DataAccessKind.None,
        SystemDataAccess = SystemDataAccessKind.None,
        IsDeterministic = true,
        IsPrecise = true,
        Name = "IntervalDescription"
        )
    ]
    [return: SqlFacet(IsFixedLength = false, IsNullable = false, MaxSize = 100)]
    public static string IntervalDescription(DateTime From, DateTime To)
    {
        var workDate = From;
        int years = To.Year - From.Year;
        int months = 0;
        int days = 0;

        if (years != 0)
        {
            if (From.Month > To.Month || (From.Month == To.Month && From.Day > To.Day))
            {
                years--;
            }
            workDate = workDate.AddYears(years);
        }

        while (workDate < To && (workDate.Year != DateTime.MaxValue.Year || workDate.Month != DateTime.MaxValue.Month))
        {
            if (workDate.AddMonths(1) <= To)
            {
                months++;
                workDate = workDate.AddMonths(1);
            }
            else
            {
                break;
            }
        }

        while (workDate < To)
        {
            days++;
            workDate = workDate.AddDays(1);
        }

        StringBuilder sb = new StringBuilder(100);

        if (years > 0)
        {
            sb.Append(years);
            sb.Append(years == 1 ? " year" : " years");
            sb.Append((months > 0 || days > 0) ? ", " : string.Empty);
        }

        if (months > 0)
        {
            sb.Append(months);
            sb.Append(months == 1 ? " month" : " months");
            sb.Append(days > 0 ? ", " : string.Empty);
        }

        if (days > 0 || (years == 0 && months == 0))
        {
            sb.Append(days);
            sb.Append(days == 1 ? " day" : " days");
        }

        return
            sb.ToString();

    }
}

SQL Server 2008R2 SP2'de uygulanan sürümüm.

CREATE FUNCTION dbo.ReadableInterval(
    @FromDate AS date,
    @ToDate AS date
)
RETURNS TABLE AS RETURN 
(
with YearStep as
(
    select
        max(n1.Number) as YearNumber
    from dbo.Numbers as n1
    where n1.Number <= DATEDIFF(YEAR, @FromDate, @ToDate)  -- see comment (A)
    and DATEADD(YEAR, n1.Number, @FromDate) <= @ToDate     -- see comment (B)
)
, MonthStep as
(
    select
        max(n2.Number) as MonthNumber
    from dbo.Numbers as n2
    cross apply YearStep as y1
    where n2.Number <= DATEDIFF(MONTH, DATEADD(YEAR, y1.YearNumber, @FromDate), @ToDate)
    and DATEADD(MONTH, n2.Number, DATEADD(YEAR, y1.YearNumber, @FromDate)) <= @ToDate
)
, DayStep as
(
    select
        DATEDIFF(day, DATEADD(MONTH, m1.MonthNumber, DATEADD(YEAR, y2.YearNumber, @FromDate)), @ToDate) as DayNumber
    from MonthStep as m1
    cross apply YearStep as y2
)
select
    y.YearNumber,
    m.MonthNumber,
    d.DayNumber
from YearStep as y
cross apply MonthStep as m
cross apply DayStep as d
)

Verilen test verileri ile sonuçlar

select
    td.FromDate,
    td.ToDate,
    td.ExpectedResult,
    ri.YearNumber as Years,
    ri.MonthNumber as Months,
    ri.DayNumber as [Days]
from dbo.TestData as td
cross apply dbo.ReadableInterval(td.FromDate, td.ToDate) as ri;

FromDate   ToDate     ExpectedResult               Years Months Days
---------- ---------- ---------------------------- ----- ------ ----
1999-12-31 1999-12-31 0 days                           0      0    0
1999-12-31 2000-01-01 1 day                            0      0    1
2000-01-01 2000-02-01 1 month                          0      1    0
2000-02-01 2000-03-01 1 month                          0      1    0
2000-01-28 2000-02-29 1 month, 1 day                   0      1    1
2000-01-01 2000-12-31 11 months, 30 days               0     11   30
2000-02-28 2000-03-01 2 days                           0      0    2
2001-02-28 2001-03-01 1 day                            0      0    1
2000-01-01 2001-01-01 1 year                           1      0    0
2000-01-01 2011-01-01 11 years                        11      0    0
9999-12-30 9999-12-31 1 day                            0      0    1
1900-01-01 9999-12-31 8099 years 11 months 30 days  8099     11   30

açıklama

Genel yaklaşımım, ilk yıllardan, önce yıllar sonra aylar sonra günler olarak ilerlemektir. Her ayrıntı düzeyinde, hedef, bitiş tarihine geçmeden yaklaşmak, ardından bir sonraki alt seviyeye devam etmektir.

Ben -yakın-değil-over hesaplama kolaylaştırmak için bir sayı tablosu kullanın. Bu tablodan ve DATEADDben ToDatekodda yorum (B) öncesinde en çok yıl / ay / gün bulabilirsiniz .

MAX numarasını aradığımdan ve Numaralarım tablosunun üzerinde kümelenmiş olduğundan, optimize edici değerleri DATEADD'ye besleyen azalan bir tarama gerçekleştiriyordu. Sayılar 100.000'den fazla satır içerdiğinden bu, tarih taşması hatalarına neden oluyordu. DATEADD(YEAR, 100000, @FromDate)9999-12-31'den büyükse ve bir hata oluşur. Tahmin (A), geriye doğru taramanın başladığı Sayı değeri üzerinde bir üst sınır verir ve tarih taşmasını önler. Sonuç olarak, sorgu planı çok büyük tarih aralıkları için bile çok az sayıda satırdan geçer.

Bu yaklaşım yıllar ve aylar bulmak için kullanılır, ancak ayların başlangıç ​​noktası ilk CTE'de bulduğum yıllar boyunca ortaya çıkar. DAYS benim en düşük ayrıntı düzeyim olduğundan basit bir DATEDIFF yeterlidir.

Bu, daha küçük bir ayrıntı düzeyine genişletilebilir ve gerekirse aralık, saat, dakika ve saniye olarak döndürülür.

PostgreSQL, agekutudan çıkar çıkmaz fonksiyonu destekler :

select
  FromDate,
  ToDate,
  ExpectedResult,
  age(ToDate, FromDate)
from TestData;

Bu istenen sonucu verir, bazı ek zaman değerleri verir veya alır.

FromDate      ToDate        ExpectedResult                  age
----------    ----------    ----------------------------    --------------------------
1999-12-31    1999-12-31    0 days                          00:00:00
1999-12-31    2000-01-01    1 day                           1 day
2000-01-01    2000-02-01    1 month                         1 mon
2000-02-01    2000-03-01    1 month                         1 mon
2000-01-28    2000-02-29    1 month, 1 day                  1 mon 1 day
2000-01-01    2000-12-31    11 months, 30 days              11 mons 30 days
2000-02-28    2000-03-01    2 days                          2 days
2001-02-28    2001-03-01    1 day                           1 day
2000-01-01    2001-01-01    1 year                          1 year
2000-01-01    2011-01-01    11 years                        11 years
9999-12-30    9999-12-31    1 day                           1 day
1900-01-01    9999-12-31    8099 years 11 months 30 days    8099 years 11 mons 30 days

numberTablo veya taksitsiz sürüm . Michael Green'in test verileri için de aynı sonucu verir. Verilerin nerede olduğu konusunda farklılık gösterirler @FromDate > @ToDate. ReadableInterval2null değerlerinin tersine negatif değerler döndürür.

CREATE FUNCTION dbo.ReadableInterval2(
    @FromDate AS date,
    @ToDate AS date
)
RETURNS TABLE AS RETURN 
(with checkData as (
    select 
       fromDate = case when @FromDate > @ToDate then @ToDate else @FromDate end,
       toDate = case when @FromDate <= @ToDate then @ToDate else @FromDate end,
       k = case when @FromDate > @ToDate then -1 else 1 end
), MonthStep as (
    select k, FromDate, ToDate,
        YearNumber = x.months / 12,
        MonthNumber = x.months % 12
    from checkdata
    cross apply(
        select months = DATEDIFF(MONTH, FromDate, ToDate)
            - case when DAY(FromDate) > DAY(ToDate) then 1 else 0 end
        ) x
)
select YearNumber = k*YearNumber, 
      MonthNumber = k*MonthNumber,
      DayNumber = k*DATEDIFF(day, DATEADD(MONTH, MonthNumber, DATEADD(YEAR, YearNumber, FromDate)), ToDate) 
    from MonthStep 
)