Question

我有两张桌子。帐户表和事务表。我想列出所有帐户的上次交易。需要左连接，因为可能存在没有事务的情况。

我有类似

的东西

select * from Account ac left join Transaction trans on ac.id = trans.acc_id

但这将列出所有交易数据。不知道我怎么能修改它。

Answer 1

您可以尝试加入Account表，只包含您的Transaction表中与每个acc_id的最大ID相对应的acc_id：

      select ac.*, t.* from Account ac left join (select acc_id, max(id) from Transaction group by acc_id) trans on ac.id = trans.acc_id left join Transaction t on trans.id=t.id

Answer 2

第一个左连接会获取该帐户的最后一个\ max事务ID。第二个左连接将获取最后一个ID的所有交易信息。

select ac.*, lasttrans.*
from Account ac 
left join (select acc_id, max(id) as id from Transaction group by acc_id) transmax 
     on ac.id = transmax.acc_id
left join Transaction lasttrans on lasttrans.id = transmax.id

Answer 3

只需使用aggregate功能以及group by

即可

select * from 
from Account ac left join Transaction trans 
on ac.id = trans.acc_id
where trans.id in (select max(id) from trans group by ac.id)

id或日期，您希望获得max ...

的列

Answer 4

这接近你的预期吗？

with acc as
(select 1 acc_id, 'name1' acc_name from dual union
select 2 acc_id, 'name2' acc_name from dual union
select 3 acc_id, 'name3' acc_name from dual),
trans as
(select 1 trans_id, 1 trans_acc_id, 'transaction detail 1' transdtl from dual
union
select 2 trans_id, 1 trans_acc_id, 'transaction detail 2' transdtl from dual
union
select 3 trans_id, 1 trans_acc_id, 'transaction detail 3' transdtl from dual
union
select 4 trans_id, 3 trans_acc_id, 'transaction detail 4' transdtl from dual
union
select 5 trans_id, 5 trans_acc_id, 'transaction detail 5' transdtl from dual
)
select * from acc, trans
where acc.acc_id = trans.trans_acc_id 
and trans.trans_id in  (select max(trans_id) from trans inner_trans where 
inner_trans.trans_acc_id = acc.acc_id)

回应是：

ACC_ID|ACC_NAME|TRANS_ID|TRANS_ACC_ID|TRANSDTL
1   |name1  |3  |1  |transaction detail 3
3   |name3  |4  |3  |transaction detail 4

带有一对多行的SQL左外连接

4 个答案: