MySql：汇总每个类别和类型的最新银行存款金额

我有四个MySql表（此处简化）：

表1：派系（仅供参考）

表2：货币（仅供参考）

表3：事件（仅供参考的列表）

表4：事件银行业务（每次事件后输入的数据，每组每种货币的剩余金额）

注意：派系2没有为事件2存入货币3

我希望能够做到的是，对于每种货币，得到每个派系最后一次存入银行（日期）的总数。（即如果所有派系合并，每种货币目前总共有多少存入银行）

所以，我需要一张看起来像这样的桌子：

currency_id | total
          1 |   130  (eg 20 + 110)
          2 |   190  (eg 50 + 140)
          3 |   250  (eg 80 + 170) <- Uses Event 3 for Group 2 as Event 2 doesn't exist

currency_id|总计
1 | 130（如20+110）
2 | 190（如50+140）
3 | 250（如80+170）我想你可以继续这样做：

select eb.currency_id, sum(amount) as total 
from events e 
inner join (
   select faction_id, currency_id, max(date) as md
   from event_banking eb
   inner join events e
   on eb.event_id = e.id
   group by faction_id, currency_id
) a 
on e.date = a.md
inner join event_banking eb
on e.id = eb.event_id
and a.faction_id = eb.faction_id
and a.currency_id = eb.currency_id
group by currency_id;

这是

id | name   | date
 1 | Evebt1 | 2013-10-16
 2 | Event2 | 2013-10-18 (Note: date out of order)
 3 | Event3 | 2013-10-17

id | faction_id | currency_id | event_id | amount
 1 |          1 |           1 |        1 |     10
 2 |          1 |           1 |        2 |     20
 3 |          1 |           1 |        3 |     30
 4 |          1 |           2 |        1 |     40
 5 |          1 |           2 |        2 |     50
 6 |          1 |           2 |        3 |     60
 7 |          1 |           3 |        1 |     70
 8 |          1 |           3 |        2 |     80
 9 |          1 |           3 |        3 |     90
10 |          2 |           1 |        1 |    100
11 |          2 |           1 |        2 |    110
12 |          2 |           1 |        3 |    120
13 |          2 |           2 |        1 |    130
14 |          2 |           2 |        2 |    140
15 |          2 |           2 |        3 |    150
16 |          2 |           3 |        1 |    160
17 |          2 |           3 |        3 |    170

currency_id | total
          1 |   130  (eg 20 + 110)
          2 |   190  (eg 50 + 140)
          3 |   250  (eg 80 + 170) <- Uses Event 3 for Group 2 as Event 2 doesn't exist

select eb.currency_id, sum(amount) as total 
from events e 
inner join (
   select faction_id, currency_id, max(date) as md
   from event_banking eb
   inner join events e
   on eb.event_id = e.id
   group by faction_id, currency_id
) a 
on e.date = a.md
inner join event_banking eb
on e.id = eb.event_id
and a.faction_id = eb.faction_id
and a.currency_id = eb.currency_id
group by currency_id;