在做Sql Server开发的时候有时需要获取表中今天、昨天、本周、上周、本月、上月等数据，这时候就需要使用DATEDIFF()函数及GetDate()函数了。

DATEDIFF ( datepart , startdate , enddate )

释义：计算时间差

datepare值：year | quarter | month | week | day | hour | minute | second | millisecond

startdate：开始日期

enddate ：结束日期

GetDate()释义：获取当前的系统日期

下面例子中,表名为tablename,条件字段名为inputdate

查询今天:SELECT * FROM tablename where DATEDIFF(day,inputdate,GETDATE())=0

查询昨天:SELECT * FROM tablename where DATEDIFF(day,inputdate,GETDATE())=1

查询明天:SELECT * FROM tablename where DATEDIFF(day,inputdate,GETDATE())=-1

查询本周:SELECT * FROM tablename where datediff(week,inputdate,getdate())=0

查询上周:SELECT * FROM tablename where datediff(week,inputdate,getdate())=1

查询下周:SELECT * FROM tablename where datediff(week,inputdate,getdate())=-1

查询本月:SELECT * FROM tablename where DATEDIFF(month,inputdate,GETDATE())=0

查询上月:SELECT * FROM tablename where DATEDIFF(month,inputdate,GETDATE())=1

查询下月:SELECT * FROM tablename where DATEDIFF(month,inputdate,GETDATE())=-1