MS Access SQL-捕获状态随时间的变化

我有一个Access 2007数据库，可以跟踪文档随时间的进展。进展如下：

创造

送审

回顾

送审

批准

我为文档状态的更改创建了一个历史记录表，其列如下：

hist_id    doc_id    month   step    status  datestamp

我创建了一个查询，返回月末的状态，如下所示：

SELECT doc_id, month, step, status, datestamp
FROM hist
WHERE (((hist.datestamp) In 
(
      Select Top 1 h.[datestamp]
      From hist as h
      Where h.[doc_id] = hist.[doc_id] and h.[month] = hist.[month]
      Order By h.[datestamp] DESC))
)
ORDER BY month, doc_id DESC;

得到

doc_id  month   step status             datestamp
a       2011-01 2    sent for review    18/01/2011
b       2011-02 1    created            01/02/2011
a       2011-02 3    reviewed           19/02/2011
c       2011-03 1    created            07/03/2011
d       2011-03 1    created            08/03/2011
e       2011-06 1    created            14/06/2011
f       2011-07 1    created            05/07/2011
g       2011-07 4    sent for approval  18/07/2011
h       2011-07 2    sent for review    14/07/2011
f       2011-08 3    reviewed           29/08/2011
g       2011-08 5    approved           17/08/2011
h       2011-08 1    created            10/08/2011
e       2011-09 3    reviewed           17/09/2011

但我真正需要的是，我的查询还可以在几个月内返回状态没有改变的文档。例如，文档

a

的状态在

19/02/2011

上变成了

revieved

，但这是它最后一次出现在上面的结果中。事实上，它应该在每个月之后以

已审核

的形式出现，直到后来成为

发送审批

所以我试图修改我的查询（或查询上面的查询）以提供如下结果

 doc_id month   step    status          datestamp
a   2011-01 2   sent for review     18/01/2011
a   2011-02 3   reviewed        19/02/2011
b   2011-02 1   created         01/02/2011
a   2011-03 3   reviewed        19/02/2011
b   2011-03 1   created         01/02/2011
c   2011-03 1   created         07/03/2011
d   2011-03 1   created         08/03/2011
a   2011-04 3   reviewed        19/02/2011
b   2011-04 1   created         01/02/2011
c   2011-04 1   created         07/03/2011
d   2011-04 1   created         08/03/2011
a   2011-05 3   reviewed        19/02/2011
b   2011-05 1   created         01/02/2011
c   2011-05 1   created         07/03/2011
d   2011-05 1   created         08/03/2011
a   2011-06 3   reviewed        19/02/2011
b   2011-06 1   created         01/02/2011
c   2011-06 1   created         07/03/2011
d   2011-06 1   created         08/03/2011
e   2011-06 1   created         14/06/2011
a   2011-07 3   reviewed        19/02/2011
b   2011-07 1   created         01/02/2011
c   2011-07 1   created         07/03/2011
d   2011-07 1   created         08/03/2011
e   2011-07 1   created         14/06/2011
f   2011-07 1   created         05/07/2011
g   2011-07 4   sent for appr   18/07/2011
h   2011-07 2   sent for rev    14/07/2011
a   2011-08 3   reviewed        19/02/2011
b   2011-08 1   created         01/02/2011
c   2011-08 1   created         07/03/2011
d   2011-08 1   created         08/03/2011
e   2011-08 1   created         14/06/2011
f   2011-08 3   reviewed        29/08/2011
g   2011-08 5   approved        17/08/2011
h   2011-08 1   created         10/08/2011
a   2011-09 3   reviewed        19/02/2011
b   2011-09 1   created         01/02/2011
c   2011-09 1   created         07/03/2011
d   2011-09 1   created         08/03/2011
e   2011-09 1   reviewed        17/09/2011
f   2011-09 3   reviewed        29/08/2011
g   2011-09 5   approved        17/08/2011
h   2011-09 1   created         10/08/2011

---

谢谢你的帮助。。。我真的不知道从哪里开始。

这在SQL中工作，不使用任何特殊功能，因此也应该在MS-ACCESS SQL中工作

首先，您需要创建一个月表

create table monthly (monthN char(7))

insert into monthly values('2011-01')
insert into monthly values('2011-02')
...

并用你需要的所有月份填充它

生成该表后，以下查询将返回您要查找的内容：

select d1.doc_id,d1.monthN,d1.step,d1.status,d1.dateStamp
from monthly m1
join docs d1 on d1.monthN=m1.monthN
union
select d2.doc_id,zz.monthN,d2.step,d2.status,d2.dateStamp
from docs d2
join
(
    select aa.doc_id,aa.monthN,bb.EndM from
    (
    select yy.doc_id,yy.monthN from
    (   
        select d3.doc_id,m2.monthN
        from monthly m2
        join (select distinct doc_id from docs) d3 on 1=1
        ) yy
    left join docs xx on xx.doc_id=yy.doc_id and xx.monthN=yy.MonthN
    where xx.hist_id is null
    ) aa
    join (select doc_id,MIN(monthN) as startM,MAX(monthN) as EndM 
          from docs group by doc_id) 
          bb on bb.doc_id=aa.doc_id and aa.monthN>=bb.StartM
) zz
on zz.doc_id=d2.doc_id and zz.EndM=d2.monthN
order by d1.monthN,d1.doc_id 

---

我建议单独运行每个内部查询，以帮助跟踪正在执行的操作…

多亏了Sparky回答中的一些线索，我才能够拼凑出适合我的东西

台阶

创建一个

months

表以包含月份列表，如

2011-08

创建

month\u range

查询，从实际文档中获取月份范围

从月份中选择月份号，其中月份介于（历史记录的最小月份）和（历史记录的最大月份）之间

---

使用

month\u range

和

hist

表进行跨产品查询，其中

hist.month\u no

Wow，非常感谢！我还没有机会尝试，但我忘了在我的问题中提到，如果未获得批准，状态可以倒退，即

发送以供批准

返回到

已审查

。你知道你的解决方案是否能解决这个问题吗？i、 e.不查找一个月内的最高状态，而是查找该月内日期最高的状态。如果没有该月的记录，则应使用最新状态。如果没有，请告诉我，我将接受一个ppekIt，因为该查询似乎没有返回所需的输出。yy的1=1部件在MS Access中不工作。是否打算创建交叉联接？MS Access中的sytax是

select*表1、表2

，因此我进行了更新以反映。它仍然不工作，我花了一些时间尝试调试。我想不出来，但从你的答案中得到一些线索（交叉连接，几个月的表格），我就能够自己从那里拼凑起来。谢谢你的帮助！

SELECT xx.month_no, xx.swp, xx.hist_id, h.status

FROM 
(
     SELECT zz.month_no, zz.swp, Max(zz.hist_id) AS hist_id
     FROM 
     (
          SELECT * FROM month_range AS mr, hist AS h 
          WHERE h.[first_of_month] <= mr.[first_of_month]
     ) zz
     GROUP BY zz.month_no, zz.swp

)  xx 

INNER JOIN hist as h ON xx.hist_id = h.hist_id;