问题描述
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我的要求是编写一个SQL查询,以获取针对托管对象发生的分区明智(故障)事件计数。我的数据库是postgres 8.4。让我解释一下表结构。
我在Django中的表格:
被管理对象:
class Managedobject(models.Model):
name = models.CharField(max_length=200,unique=True)
iscontainer = models.BooleanField(default=False,)
parentkey = models.ForeignKey(\'self\',null=True)
活动表:
class Event(models.Model):
Name = models.CharField(verbose_name=_(\'Name\'))
foid = models.ForeignKey(Managedobject)
被管理对象记录:
NOC
Chennai
MO_1
MO_2
MO_3
Mumbai
MO_4
MO_5
MO_6
Delhi
Bangalore
IP
Calcutta
Cochin
活动记录:
event1 MO_1
event2 MO_2
event3 MO_3
event4 MO_5
event5 MO_6
现在,我需要获取所有子区域的事件计数。例如,
for NOC region:
Chennai - 3
Mumbai - 2
Delhi - 0
Bangalore - 0
到目前为止,我能够通过两个不同的查询获得结果。
获取子区域。
select id from managedobject where iscontainer = True and parentkey = 3489
对于每个区域(使用for循环),按如下方式获取计数:
SELECT count(*)
from event ev
WHERE ev.foid
IN (
WITH RECURSIVE q AS (
SELECT h
FROM managedobject h
WHERE parentkey = 3489
UNION ALL
SELECT hi
FROM q
JOIN managedobject hi
ON hi.parentkey = (q.h).id
)
SELECT (q.h).id FROM q
)
请帮助组合查询以使其成为单个查询并获取前5个区域。由于在django中查询很困难,因此我要进行原始SQL查询。
解决方法
我得到了查询:
WITH RECURSIVE q AS (
SELECT h,1 AS level,id AS ckey,displayname as dname
FROM managedobject h
WHERE parentkey = 3489
and logicalnode=True
UNION ALL
SELECT hi,q.level + 1 AS level,ckey,dname
FROM q
JOIN managedobject hi ON hi.parentkey = (q.h).id
)
SELECT count(ckey) as ccount,dname
FROM q
JOIN event as ev on ev.foid_id = (q.h).id
GROUP BY ckey,dname
ORDER BY ccount DESC
LIMIT 5