SqlServer中 SET DATEFIRST更改

SET DATEFIRST 1   --定义日期周一开始 

SELECT @@DATEFIRST  --7
SELECT DATENAME(WEEK,‘2013-12-31‘) AS WeekName  -- 53
SELECT DATENAME(WEEK,‘2014-01-01‘) AS WeekName  -- 1
SELECT DATENAME(WEEK,‘2014-01-05‘) AS WeekName  -- 2

IF OBJECT_ID(‘DimDateStartWithMonday‘,‘U‘) IS NOT NULL
DROP TABLE DimDateStartWithMonday
GO

CREATE TABLE DimDateStartWithMonday
(
    DateKey INT PRIMARY KEY,
    FullDate DATE NOT NULL,
    [DateName] NVARCHAR(20),
    DayNumberOfWeek TINYINT NOT NULL,
    DayNameOfWeek NVARCHAR(10) NOT NULL,
    DayNumberOfMonth TINYINT NOT NULL,
    DayNumberOfYear SMALLINT NOT NULL, 
    WeekNumberOfYear TINYINT NOT NULL,
    EnglishMonthName NVARCHAR(10) NOT NULL,
    MonthNumberOfYear TINYINT NOT NULL,
    CalendarQuarter TINYINT NOT NULL,
    CalendarSemester TINYINT NOT NULL,
    CalendarYear SMALLINT NOT NULL 
)

DECLARE @StartDate DATETIME
DECLARE @EndDate DATETIME

SELECT @StartDate = ‘2001-01-01‘,
       @EndDate = ‘2035-12-31‘

	   WHILE(@StartDate<+@EndDate)
	   BEGIN
        INSERT INTO DimDateStartWithMonday 
    (
        DateKey,
        FullDate,
        [DateName],
        DayNumberOfWeek,
        DayNameOfWeek,
        DayNumberOfMonth,
        DayNumberOfYear, 
        WeekNumberOfYear,
        EnglishMonthName, 
        MonthNumberOfYear,
        CalendarQuarter,
        CalendarSemester,
        CalendarYear 
    )
    SELECT CAST(CONVERT(VARCHAR(8),@StartDate,112) AS INT) AS DateKey,
           CONVERT(VARCHAR(10), @StartDate,20) AS FullDate,
           CONVERT(VARCHAR(20), @StartDate,106) AS [DateName],
           DATEPART(DW,@StartDate) AS DayNumberOfWeek,
           DATENAME(DW,@StartDate) AS DayNameOfWeek,
           DATENAME(DD,@StartDate) AS [DayOfMonth],
           DATENAME(DY,@StartDate) AS [DayOfYear],  
           DATEPART(WW,@StartDate) AS WeekNumberOfYear,
           DATENAME(MM,@StartDate) AS EnglishMonthName,
           DATEPART(MM,@StartDate) AS MonthNumberOfYear,
           DATEPART(QQ,@StartDate) AS CalendarQuarter,
           CASE WHEN DATEPART(MM,@StartDate) BETWEEN 1 AND 6
                    THEN 1
                ELSE 2
           END AS CalendarSemester,
           DATEPART(YY,@StartDate) AS CalendarYear 
SET @StartDate = @StartDate + 1
	   END
       

	   IF OBJECT_ID(‘ETLWORK_GETWEEKNUMBER‘,‘FN‘) IS NOT NULL
DROP FUNCTION ETLWORK_GETWEEKNUMBER
GO
 
CREATE FUNCTION ETLWORK_GETWEEKNUMBER(@DATE DATETIME)  
RETURNS INTEGER
AS
BEGIN 
 DECLARE @FIRST_DATE_OF_YEAR DATETIME = DATEADD(YYYY,DATEDIFF(YYYY,0,@DATE),0) 

  DECLARE @WEEK_NUMBER INTEGER

    -- 如果当前时间是当前年的第一天
    IF @DATE = @FIRST_DATE_OF_YEAR
        SET @WEEK_NUMBER = 1 
    -- 星期天是年第一天的情况
    ELSE IF (DATEPART(WEEKDAY,@DATE) = 1 AND DATEDIFF(DAYOFYEAR,@FIRST_DATE_OF_YEAR,@DATE)/7 + 1 = DATEPART(WEEK,@DATE))  
        SET @WEEK_NUMBER = DATEPART(WEEK,@DATE)  
    -- 星期天不是年第一天的情况
    ELSE IF (DATEPART(WEEKDAY,@DATE) = 1 AND DATEDIFF(DAYOFYEAR,@FIRST_DATE_OF_YEAR,@DATE)/7 + 1 <> DATEPART(WEEK,@DATE)) 
        SET @WEEK_NUMBER = DATEPART(WEEK,@DATE) - 1 
    -- 如果当前天的上一个周日小于年第一天
    ELSE IF DATEADD(DAY,-1,DATEADD(WK,DATEDIFF(WK,0,@DATE),0)) < @FIRST_DATE_OF_YEAR 
        SET @WEEK_NUMBER = 1 
    -- 当前天前面的一个周日正好是以周日为开始年的 7 倍的天数
    ELSE IF DATEDIFF(DAYOFYEAR,@FIRST_DATE_OF_YEAR,DATEADD(DAY,-1,DATEADD(WK,DATEDIFF(WK,0,@DATE),0) ))/7 + 1 = DATEPART(WEEK,@DATE) 
        SET @WEEK_NUMBER = DATEPART(WEEK,@DATE) + 1  
    ELSE 
        SET @WEEK_NUMBER = DATEPART(WEEK,@DATE)   
           
    RETURN @WEEK_NUMBER
END

DECLARE @DATE DATETIME = ‘2017-01-02‘
DECLARE @FIRST_DATE_OF_YEAR DATETIME = DATEADD(YYYY,DATEDIFF(YYYY,0,@DATE),0) 

SELECT DATEPART(WEEK,@DATE), -- 一年中的周数，默认以周日开始 
       DATEADD(WK,DATEDIFF(WK,0,@DATE),0), -- 当前周的周一，默认从周日开始，但是仍然找周一
       DATEADD(DAY,-1,DATEADD(WK,DATEDIFF(WK,0,@DATE),0)), -- 当前周先找周一，然后往前一天找到周日
       DATEDIFF(DAYOFYEAR,@FIRST_DATE_OF_YEAR,DATEADD(DAY,-1,DATEADD(WK,DATEDIFF(WK,0,@DATE),0))), -- 当前天离年第一天的间隔
       DATEDIFF(DAYOFYEAR,@FIRST_DATE_OF_YEAR,DATEADD(DAY,-1,DATEADD(WK,DATEDIFF(WK,0,@DATE),0) ))/7 + 1  -- 按天计算的周数