Question

我的表格包含字段bytes_in，mac_src和mac_dst。我想获得字段bytes_in和mac_src相等的所有行的字段mac_dst的总和，然后将此总和从最高到最低排序。返回的Queryset每个mac_src和mac_dst值只有一个条目。

换句话说，我需要总结字段bytes_in，好像mac_src和mac_dst是具有相同值的相同字段。

感谢。

+-------------------+-------------------+----------+
| mac_src           | mac_dst           | bytes_in |
+-------------------+-------------------+----------+
| aa:aa:aa:aa:aa:aa | bb:bb:bb:bb:bb:bb |       10 |
| bb:bb:bb:bb:bb:bb | aa:aa:aa:aa:aa:aa |       20 |
| cc:cc:cc:cc:cc:cc | aa:aa:aa:aa:aa:aa |       30 |
+-------------------+-------------------+----------+

Answer 1

select mac_src,sum(case when mac_src=mac_dst then bytes_in else null end)
from table
group by mac_src
order by sum(case when mac_src=mac_dst then bytes_in else null end) desc;

Answer 2

from django.db.models import F, Sum

items = (
    Item.objects
    .filter(mac_src=F('mac_dst'))
    .values('mac_src', 'mac_dst')
    .annotate(sum_bytes=Sum('bytes_in'))
    .order_by('-sum_bytes')
)

Answer 3

select
  t1.mac_src as mac,
  t1.sum_bytes_in + t2.sum_bytes_in as sum_bytes_in
from
  (select
    mac_src,
    sum(bytes_in) as sum_bytes_in
  from tbl
  group by mac_src) as t1
  inner join
  (select
    mac_dst,
    sum(bytes_in) as sum_bytes_in
  from tbl
  group by mac_dst) as t2
  on t1.mac_src = t2.mac_dst
order by sum_bytes_in desc

这假定任何行的row.mac_src！= row.mac_dst。

Django - 获取其他2个字段相等的字段总和

3 个答案: