我想合并以下SQL语句，以便将所有结果都放在一列中，而不是在4个单独的列中：
select count(incnum) as counttenth3 from kincident where (to_char(reportdate,'hh24') between 0 and 2.59 or to_char(reportdate,'hh24') between 21 and 23.59
select count(incnum) as counttenth2 from kincident where to_char(reportdate,'hh24') between 15 and 20.59
select count(incnum) as counttenth1 from kincident where to_char(reportdate,'hh24') between 9 and 14.59
select count(incnum) as counttenth0 from kincident where to_char(reportdate,'hh24') between 3 and 8.59
唯一的区别是为每个语句指定的时间范围。因此，我试图将它们全部合并为一列，并且我希望第二列包含具有给定字符串的行（不是来自数据库）
例如
Timing | count of incidents
-----------------------------
morning | 26
afternoon | 35
night | 40
像这样-未经测试，因为我通常写MS SQL :)
select
t.time_of_day,
count(t.time_of_day)
from
(
---
select
case to_char(reportdate,'hh24')
when between 15 and 20.59 then 'afternoon'
when between 9 and 14.59 then 'morning'
when between 3 and 8.59 then 'early-morning'
else 'night' --when between 0 and 2.59 or to_char(reportdate,'hh24') between 21 and 23.59
end as time_of_day
from
kincident
) t
group by
t.time_of_day
使用CASE语句对您的时间范围进行分类，我已将其放入子查询中，但是您可以将其包装在视图中；作为外部查询的一部分，我们对时间类别进行分组，然后在外部选择中进行计数。
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