在 oracle 的 sql 查询中替换 "filter"

Question

我们有一个 table 数据，其中一个日期列指示数据的日期 ("planning_day") 和另一列用于记录数据发送时间 ("first_sent_time").

我正在尝试制作一份报告，显示我们在哪一天发送了 past/future 数据。所以如果今天我们发送 2 个昨天的数据，5 个今天的数据和 1 个后天的数据，结果应该是这样的：

sent_day   minus2 minus1 sameDay plus1 plus2
2021-11-24    0      2      5      0     1
...

我知道我可以在 postgres 中通过使用“过滤器”的查询来做到这一点：

select
  trunc(t.first_sent_time),
  count(t.id) filter (where e.planning_day - trunc(e.first_sent_time) = -2) as "minus2",
  count(t.id) filter (where e.planning_day - trunc(e.first_sent_time) = -1) as "minus1",
  count(t.id) filter (where e.planning_day - trunc(e.first_sent_time) = 0)  as "sameDay",
  count(t.id) filter (where e.planning_day - trunc(e.first_sent_time) = 1)  as "plus1",
  count(t.id) filter (where e.planning_day - trunc(e.first_sent_time) = 2)  as "plus2"
from
  my_table t
group by
  trunc(t.first_sent_time)
;

不幸的是，这个“过滤器”在 Oracle 中不存在。我在这里需要帮助。我尝试了如下操作：

select 
  sent_day,
  sum(minus2),
  sum(minus1),
  sum(sameDay),
  sum(plus1),
  sum(plus2)
from (
  select 
    *
  from (
    select
      b.id,
      trunc(b.first_sent_time) as sent_day,
      b.planning_day,
      b.planning_day - trunc(b.first_sent_time) as day_diff
    from
      my_table b
    where
      b.first_sent_time >= DATE '2021-11-01'
  )
  pivot (
    count(id) for day_diff in (-2 as "minus2",-1 as "minus1",0 as "sameDay", 1 as "plus1",2 as "plus2")
  )
)
group by
  sent_day
order by
  sent_day
;

但它不起作用，感觉我走得太复杂了，必须有一个更简单的解决方案。

Answer 1

在聚合函数中使用CASE表达式来模拟filter。

这里是一个简化的例子

with dt as (
select 1 id , 1 diff_days from dual union all
select 2 id , 1 diff_days from dual union all
select 3 id , -1 diff_days from dual union all
select 4 id , -1 diff_days from dual union all
select 4 id , -1 diff_days from dual)
/* query */
select 
  count(case when diff_days = 1 then id end) as cnt_1,
  count(case when diff_days = -1 then id end) as cnt_minus_1
from dt;

结果

     CNT_1 CNT_MINUS_1
---------- -----------
         2           3

在 oracle 的 sql 查询中替换 "filter"

substituting "filter" in a sql query on oracle

sql

oracle

pivot

group-by