Sum 的注释似乎不起作用 Django答案

【问题标题】：The annotate with Sum seems doesn't work DjangoSum 的注释似乎不起作用 Django
【发布时间】：2020-08-21 07:18:00
【问题描述】：

有一个如下的 db (mysql) 表：

class AccountsInsightsHourly(models.Model):
    account_id = models.CharField(max_length=32, blank=True, null=True)
    spend = models.DecimalField(max_digits=12, decimal_places=2, blank=True, null=True)
    date = models.IntegerField(blank=True, null=True)
    hour = models.IntegerField(blank=True, null=True)
    created_time = models.DateTimeField(blank=True, null=True)

    class Meta:
        managed = False
        db_table = 'accounts_insights_hourly'
        unique_together = (('account_id', 'date', 'hour'),)
        ordering = ["account_id", "hour"]

有些数据保存在 db 中是这样的：

id  account_id    spend    date        hour   created_time 

1     1222         200     20200820    12      ....
1     1222         300     20200820    14      ....

我尝试获取每个帐户在指定日期的最大支出。

base_queryset_yesterday = AccountsInsightsHourly.objects.filter(date=date_yesterday). \
            annotate(yesterday_spend=Max("spend", output_field=FloatField())). \
            values("account_id", "yesterday_spend")

# I got results like below

<QuerySet [{'account_id': '1222', 'yesterday_spend': 200}, {'account_id': '1222', 'yesterday_s
pend': 300}]>




# expected result is 

<QuerySet [{'account_id': '1222', 'yesterday_spend': 300}>

如何使注释按预期工作？

更新

感谢ruddra 的帮助，正确的查询集应该是

base_queryset_yesterday = AccountsInsightsHourly.objects.filter(date=date_yesterday).values("account_id"). \
            annotate(yesterday_spend=Max("spend", output_field=FloatField())). \
            values("account_id", "yesterday_spend").\
            order_by()

interaction-with-default-ordering-or-order-by

【问题讨论】：

标签： django

【解决方案1】：

你可以这样试试：

base_queryset_yesterday = AccountsInsightsHourly.objects.filter(date=date_yesterday).values("account_id"). \
            annotate(yesterday_spend=Max("spend", output_field=FloatField())). \
            values("account_id", "yesterday_spend")

它将生成一个GROUP_BY 查询，如下所示：

'SELECT "accounts_insights_hourly"."account_id", MAX("accounts_insights_hourly"."spend") AS "yesterday_spend" FROM "accounts_insights_hourly" WHERE "accounts_insights_hourly"."date" = 2020-08-21 GROUP BY "accounts_insights_hourly"."account_id"'

【讨论】：

感谢回复，但它回复了我<QuerySet [{'yesterday_spend': 200}, {'yesterday_spend': 300}]>
你能看到更新的答案吗？它应该返回查询：'SELECT "AccountsInsightsHourly"."account_id", MAX("AccountsInsightsHourly"."spend") AS "yesterday_spend" FROM "AccountsInsightsHourly" GROUP BY "AccountsInsightsHourly"."account_id"'
仍然得到相同的结果，并且打印的sql query 显示分组依据是`GROUP BY accounts_insights_hourly.account_id, accounts_insights_hourly.`hour`` 这让我很困惑。
感谢您的耐心等待，我在查询集末尾添加了order_by()，终于成功了。