SQL 输出某一天所在的年月对应的所有星期的开始与结束日期（每个月仅算4周，第四周可能会有10天）

背景：有时侯导报表需要动态计算每个月对应每周的第一天与最后一天。最后一周的时间要求不需要仅精确到第7天，可以算10天。

USE [***]
GO

/****** Object:  StoredProcedure [dbo].[sp_CalcStartDateEndDateForSingleYearMonthInDate]    Script Date: 2016/2/25 14:28:26 ******/
DROP PROCEDURE [dbo].[sp_CalcStartDateEndDateForSingleYearMonthInDate]
GO

/****** Object:  StoredProcedure [dbo].[sp_CalcStartDateEndDateForSingleYearMonthInDate]    Script Date: 2016/2/25 14:28:26 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO







/*
  
  exec [sp_CalcStartDateEndDateForSingleYearMonthInDate] '2016-1-1'
  exec [sp_CalcStartDateEndDateForSingleYearMonthInDate] '2015-10-1'
  exec [sp_CalcStartDateEndDateForSingleYearMonthInDate] '2015-9-1'
  exec [sp_CalcStartDateEndDateForSingleYearMonthInDate] '2014-3-1'

*/

CREATE PROC [dbo].[sp_CalcStartDateEndDateForSingleYearMonthInDate](
  @SingleDate datetime
)
AS
BEGIN
   
      
  DECLARE @month VARCHAR(2)
  DECLARE @year VARCHAR(4)

  DECLARE @FirstDayInFeb DATETIME
  DECLARE @LastDayInFeb DATETIME

  if(@SingleDate is null)
    set @SingleDate=getdate()

  SET @month= MONTH(@SingleDate)
  SET @year=YEAR(@SingleDate)

  SET @FirstDayInFeb = CONVERT(DATETIME, @year+'-02-01')
  SET @LastDayInFeb = DATEADD(M, 1, @FirstDayInFeb)
  SET @LastDayInFeb = DATEADD(D, -1, @LastDayInFeb)


  --drop table @tWeek

  --CREATE TABLE @tWeek
  --(
  --startDate VARCHAR(10),
  --endDate VARCHAR(10),
  --weekIndex INT
  --)

  declare  @tWeek TABLE
   (
    startDate VARCHAR(10),
    endDate VARCHAR(10),
    weekIndex INT
  )

  INSERT INTO @tWeek VALUES  ( @year+'-'+@month+'-1',@year+'-'+@month+'-7', 1)
  INSERT INTO @tWeek VALUES  ( @year+'-'+@month+'-8',@year+'-'+@month+'-14', 2)
  INSERT INTO @tWeek VALUES  ( @year+'-'+@month+'-15',@year+'-'+@month+'-21', 3)

  IF @month IN (1,3,5,7,8,10,12)

    INSERT INTO @tWeek VALUES  ( @year+'-'+@month+'-22',@year+'-'+@month+'-31', 4)

  IF @month IN (4,6,9,11)

    INSERT INTO @tWeek VALUES  ( @year+'-'+@month+'-22',@year+'-'+@month+'-30', 4)

  IF @month=2

    INSERT INTO @tWeek VALUES  (  @year+'-'+@month+'-22',  CONVERT(VARCHAR(10),@LastDayInFeb,120),4)


  SELECT * FROM @tWeek


  
END
 







GO

运行结果：