如何在WHERE子句中动态调用日期而不是硬编码？

Question

在我使用SQL Server的代码中，我比较了两个月之间我确定确切日期的数据。我正在尝试查找某些列中的值是否会在一些不同的情况下发生变化。这部分工作，但我想要做的是，使我不必总是回去改变日期，每次我想获得我期待的结果。这可能吗？我至今是：

with 
dates as (
select distinct 
d.Date 
from Database d 
WHERE 
d.Date IN (
    SELECT MAX(Date) 
    FROM  Database 
    group by YEAR(Date), MONTH(Date) 
    ) 


) 

select 
    case 
    when (t1.[Mapping Status] = '0' and t2.[Mapping Status]= '0') or (t1.[Mapping Status] = '1' and t2.[Mapping Status] = '1') 
    then 'No Change' 
    when t1.[Mapping Status] = '0' and t2.[Mapping Status]= '1' 
    then 'Newly Changed in Status' 
    when t1.[Mapping Status] = '1' and t2.[Mapping Status] = '0' 
    then 'Resolved' 
    when t1.[Mapping Status] is null and t2.[Mapping Status] = '1' 
    then 'New Resolved' 
    when t1.[Mapping Status] is null and t2.[Mapping Status] = '0' 
    then 'New Not Resolved' 
    when t2.[Mapping Status] is null and t1.[Mapping Status] = '1' 
    then 'Instance Retired' 
    when t2.[Mapping Status] is null and t1.[Mapping Status] = '0' 
    then 'Instance Not Retired' 
    else 
    'Status Remains Missing' 
    end as [Status Change] 
    , * 
    from Database t1 
    full join Database t2 on t1.Column = t2.Column 
    left join dates d on d.Date = t1.Date 

    where t1.date like '01-31-2017' 
    and t2.date like '02-28-2017' 
    order by [Status Change] 

我的想法是，添加一个WITH子句，我可以得到的maxDate然后，而不是调用确切一天下来，我在那里我可以使用类似：

where t1.date like max(getdate()-1) 
and t2.date like max(getdate()) 

但它给我一个聚合错误。无论如何，我可以将这个日期问题简单化吗？在此先感谢

编辑

好吧，我想澄清一下。在我的发言，我有：

select distinct 
d.Date 
from Database d 

将返回：

+------+-------------+ 
|  | Date  | 
+------+-------------| 
| 1 | 01-06-2017 | 
| 2 | 01-13-2017 | 
| 3 | 01-20-2017 | 
| 4 | 01-27-2017 | 
| 5 | 02-03-2017 | 
| 6 | 02-10-2017 | 
| 7 | 02-17-2017 | 
| 8 | 02-24-2017 | 
| 9 | ........ | 
+------+-------------+ 

如果我选择该语句并执行，它会从我的表如上图所示只返回日期。我想要做的是能够得到从这些日期值中提取的sql，并比较从一个月的最后日期值到下一个月的最后日期值。实质上，它应该将日期8的值与日期4的值进行比较，但它应该足够动态，以便可以在没有太多修补的情况下为任何两个日期执行相同的操作。

Answer 1

如果我没有误解您的请求，看起来您需要一个数字表，也称为理货表，或者在这种情况下是日历表。

推荐岗位：https://dba.stackexchange.com/questions/11506/why-are-numbers-tables-invaluable

基本上，你创建一个表，并与今年的第0周开始和结束日期的数字来填充它。然后将您的主查询加入此表。

+------+-----------+----------+ 
| week | startDate | endDate | 
+------+-----------+----------+ 
| 1 | 20170101 | 20170107 | 
| 2 | 20170108 | 20170114 | 
+------+-----------+----------+ 

Select b.week, max(a.data) from yourTable a 
inner join calendarTable b 
    on a.Date between b.startDate and b.endDate 
group by b.week 

Answer 2

动态日期，以滤除BETWEEN

select dateadd(m,-1,dateadd(day,-(datepart(day,cast(getdate() as date))-1),cast(getdate() as date))) -- 1st date of last month 

select dateadd(day,-datepart(day,cast(getdate() as date)),cast(getdate() as date)) -- last date of last month 

select dateadd(day,-(datepart(day,cast(getdate() as date))-1),cast(getdate() as date)) -- 1st date of current month 

select dateadd(day,-datepart(day,dateadd(m,1,cast(getdate() as date))),dateadd(m,1,cast(getdate() as date))) -- last date of the month