当前时间周的起始日期（以周一为例）select DATEADD(week,DATEDIFF(week,0,getdate()),0)
上周起始：select dateadd(week,-1,DATEADD(week,DATEDIFF(week,0,getdate()),0))
上上周起始：select dateadd(week,-2,DATEADD(week,DATEDIFF(week,0,getdate()),0))
上上上周起始：select dateadd(week,-3,DATEADD(week,DATEDIFF(week,0,getdate()),0))
周七以此类推
sql如何通过当前日期获取上周，上上周，上上上周的起始日期（周一_周七）
原文：http://www.cnblogs.com/amylis_chen/p/7726214.html