Question

这些行中都有表格：

A：

id   param_1   param_2    status     dateUpdated
-----------------------------------------------
1    valuea   valueb    Active      2018-10-02
2    valuec   valued    Inactive    2018-09-03
3    valuee   valuef    Active      2018-10-01
4    valueg   valueh    Active      2017-01-20
5    value1   value2    Active      2018-03-03
6    value3   value4    Active      2016-10-21
...

B：

id    a_id   some_param    dateModified
-------------------------------------
1     3      x             2018-10-04 
2     2      y             2018-06-30
3     4      aa            2018-10-01
...
99    6      ab            2018-01-16
100   3      z             2018-04-08

我希望A中的记录在某个日期之后进行更新，但还包括与另一个表B中的日期条件匹配的其他记录（如果尚不存在，否则返回最新日期）。 / p>

如果仅表A：

select id,
       param_1, 
       param_2, 
       dateUpdated
from A
where status = 'Active'
and dateUpdated between @someDate and @someAnotherDate

现在加入：

select distinct  A.id,
                 A.param_1, 
                 A.param_2, 
                 A.dateUpdated -- or B.dateModified, whichever is latest if that's even possible
from A
join B on B.a_id = A.id
where A.status = 'Active'
and ((A.dateUpdated between @someDate and @someAnotherDate) || (B.dateModified between @someDate and @someAnotherDate))

因此，从上方说someDate = '2018-10-01'和someAnotherDate = '2018-10-04'，我将得出结果：

id,  param_1   param_2    dateUpdated
------------------------------------
1    valuea   valueb      2018-10-02
3    valuee   valuef      2018-10-04
4    valueg   valueh      2018-10-01

Answer 1

使用左连接和大小写表达式获取最新日期

select distinct  A.id,
                 A.param_1, 
                 A.param_2, 
                 case when A.dateUpdated > B.dateUpdated
                 then A.dateUpdated else B.dateUpdated end

from A
left join B on B.a_id = A.id
where A.status = 'Active'
and ((A.dateUpdated between @someDate and @someAnotherDate) 
    OR (B.dateModified between @someDate and @someAnotherDate))

Answer 2

在B中，您希望每个a_id在给定范围内的最大日期。将此结果外部加入A，然后使用CASE WHEN获取较新的日期。

select
  a.id,
  a.param_1,
  a.param_2,
  a.status,
  case when bmax.max_date > a.dateUpdated then bmax.max_date else a.dateUpdated as updated
from a
left join
(
  select a_id, max(dateModified) as max_date
  from b
  where dateModified between @someDate and @someAnotherDate
  group by a_id
) bmax on bmax.a_id = a.id
where a.status = 'Active'
and 
(
   a.dateUpdated between @someDate and @someAnotherDate
   or
   bmax.dateModified between @someDate and @someAnotherDate
)
order by a.id;

还包括此表中与sql中另一个表上的条件匹配的记录

2 个答案: