我有三个分别名为Groups,GroupMembers和DailyTable的表。以下是我为每个模型制作的模型:
models.py
class Group(models.Model):
name = models.CharField(max_length=255, blank=False, null=False)
group_type = models.ForeignKey('GroupType',blank=True,default=False)
class Meta:
db_table = 'groups'
class GroupMembers(models.Model):
group = models.ForeignKey('Group')
user = models.ForeignKey('User')
status = models.CharField(max_length=20)
class Meta:
db_table = 'group_members'
unique_together = ['group', 'user']
class DailyTable(models.Model):
class Meta:
managed = True
db_table = 'dailytable'
user_id = models.IntegerField(db_index=True)
calories = models.FloatField()
date = models.DateField()
我想计算每个小组各自消耗的总卡路里。所以我启动了以下查询:
select groups.id,groups.name as group_display_name,
(select count(*) from group_members where group_id = groups.id and status = 'accepted' and groups.group_type_id = 1) as total_members,
(select sum(calories) from dailytable where user_id in (select user_id from group_members where group_id = groups.id and groups.group_type_id = 1) and dailytable.date='2016-02-02') as total_calories,
(select case when exists(select * from group_members where group_id = groups.id and user_id = 3 and status = 'accepted' and groups.group_type_id = 1) then cast(1 as bit) else cast(0 as bit) end) as is_member_of_group
from groups
where groups.group_type_id = 1
order by total_calories desc
nulls last;
下面是我得到的输出。现在,我想根据已刻录的total_calories对组进行排名,因此我在查询中进行了以下更改:
....
dense_rank() over(order by total_calories)
from groups
....
错误: “ total_calories”列不存在
我想将RANK应用于查询的输出。有什么办法可以做到这一点。
这是因为您正在尝试在density_rank()中使用派生的列别名,该别名在此处不可用。在CTE中包装查询,并在其上应用density_rank():
WITH baseQuery AS (
SELECT
groups.id,
groups.name AS group_display_name,
(
SELECT
count(*)
FROM group_members
WHERE
group_id = groups.id AND status = 'accepted' AND groups.group_type_id = 1) AS total_members,
(
SELECT
sum(calories)
FROM dailytable
WHERE
user_id IN (
SELECT
user_id
FROM group_members
WHERE
group_id = groups.id
AND groups.group_type_id = 1
) AND dailytable.date = '2016-02-02'
) AS total_calories,
(
SELECT
CASE WHEN exists(SELECT
*
FROM group_members
WHERE
group_id = groups.id
AND user_id = 3
AND status = 'accepted'
AND groups.group_type_id = 1)
THEN cast(1 AS BIT)
ELSE cast(0 AS BIT) END) AS is_member_of_group
FROM groups
WHERE
groups.group_type_id = 1
)
select * ,
dense_rank() over(order by total_calories)
from baseQuery
ORDER BY total_calories DESC
NULLS LAST
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