Lavorare con le tabelle calendario

Analisi delle serie temporali in SQL Server

Maham Faisal Khan

Senior Data Science Content Developer

Cos'è una tabella calendario?

SELECT *
FROM dbo.Calendar;

DateKey	Date	Day	DayOfWeek	DayName	...
20000101	2000-01-01	1	7	Saturday	...
20000102	2000-01-02	2	1	Sunday	...
20000103	2000-01-03	3	2	Monday	...

Contenuto di una tabella calendario

Colonne generali

Date
Day Name
Is Weekend

Anno solare

Mese solare
Trimestre solare
Anno solare

Anno fiscale

Settimana fiscale dell'anno
Trimestre fiscale
Primo giorno dell'anno fiscale

Colonne speciali

Nome festività
Dettagli lunari
Settimana ISO dell'anno

Creare una tabella calendario

CREATE TABLE dbo.Calendar
(
    DateKey INT NOT NULL,
    [Date] DATE NOT NULL,
    [Day] TINYINT NOT NULL,
    DayOfWeek TINYINT NOT NULL,
    DayName VARCHAR(10) NOT NULL,
    ...
)

SELECT
    CAST(D.DateKey AS INT) AS DateKey,
    D.[DATE] AS [Date],
    CAST(D.[day] AS TINYINT) AS [day],
    CAST(d.[dayofweek] AS TINYINT) AS [DayOfWeek],
    CAST(DATENAME(WEEKDAY, d.[Date]) AS VARCHAR(10)) AS [DayName],
    ...

Uso di una tabella calendario

SELECT
    c.Date
FROM dbo.Calendar c
WHERE
    c.MonthName = 'April'
    AND c.DayName = 'Saturday'
    AND c.CalendarYear = 2020
ORDER BY
    c.Date;

Date
2020-04-04
2020-04-11
2020-04-18
2020-04-25

Uso di una tabella calendario

SELECT
    c.Date
FROM dbo.Calendar c
WHERE
    c.MonthName = 'April'
    AND c.DayName = 'Saturday'
    AND c.CalendarYear = 2020
ORDER BY
    c.Date;

Date
2020-04-04
2020-04-11
2020-04-18
2020-04-25

Nota rapida su APPLY()

SELECT
    FYStart =
        DATEADD(MONTH, -6,
            DATEADD(YEAR,
                DATEDIFF(YEAR, 0,
                    DATEADD(MONTH, 6, d.[date])), 0)),
    FiscalDayOfYear =
        DATEDIFF(DAY,
            DATEADD(MONTH, -6,
                DATEADD(YEAR,
                    DATEDIFF(YEAR, 0,
                        DATEADD(MONTH, 6, d.[date])), 0)), d.[Date]) + 1,
    FiscalWeekOfYear =
        DATEDIFF(WEEK,
            DATEADD(MONTH, -6,
                DATEADD(YEAR,
                    DATEDIFF(YEAR, 0,
                        DATEADD(MONTH, 6, d.[date])), 0)), d.[Date]) + 1
FROM dbo.Calendar d;

Nota rapida su APPLY()

SELECT
    fy.FYStart,
    FiscalDayOfYear = DATEDIFF(DAY, fy.FYStart, d.[Date]) + 1,
    FiscalWeekOfYear = DATEDIFF(WEEK, fy.FYStart, d.[Date]) + 1
FROM dbo.Calendar d
    CROSS APPLY
    (
        SELECT FYStart =
            DATEADD(MONTH, -6,
                DATEADD(YEAR,
                    DATEDIFF(YEAR, 0,
                        DATEADD(MONTH, 6, d.[date])), 0))
    ) fy;

Ayo berlatih!

Analisi delle serie temporali in SQL Server