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sql - 还包括此表中与 sql 中另一个表上的条件匹配的记录

问题描述

我在这些行中有表格：

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
...

乙：

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

我想要在A某个日期之后更新的记录，但还包括与另一个表中的日期条件匹配的其他记录（如果不存在，否则返回最新日期）B。

如果只有表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))

所以从上面说someDate = '2018-10-01'，someAnotherDate = '2018-10-04'我会得到结果：

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

标签： sqlsql-serversql-server-2016

解决方案

从B您想要每个给定范围内的最大日期a_id。将此结果外连接到A并用于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;

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