Oracle：基于多对多关系选择最近

Question

我有以下两个表 card_accounts 和 account_transaction。

create table card_accounts(card_number number(16),account_number number(10),status char(1));


Insert into card_accounts(card_number,account_number,status)values(123456,000001,'A');
Insert into card_accounts(card_number,account_number,status)values(123456,000002,'A');
Insert into card_accounts(card_number,account_number,status)values(223456,000003,'A');
Insert into card_accounts(card_number,account_number,status)values(223456,000004,'A');
Insert into card_accounts(card_number,account_number,status)values(33456,000004,'A');
Insert into card_accounts(card_number,account_number,status)values(523456,000007,'A');

create table account_transaction(account_number number(16),transactionId number(10),created_date DATE);


Insert into account_transaction(account_number,transactionId,created_date)values(000001,543678,TO_DATE('2003/05/03 21:02:44', 'yyyy/mm/dd hh24:mi:ss'));
Insert into account_transaction(account_number,transactionId,created_date)values(000002,543679,TO_DATE('2003/05/03 21:02:34', 'yyyy/mm/dd hh24:mi:ss'));
Insert into account_transaction(account_number,transactionId,created_date)values(000003,543680,TO_DATE('2003/05/03 18:02:44', 'yyyy/mm/dd hh24:mi:ss'));
Insert into account_transaction(account_number,transactionId,created_date)values(000004,543681,TO_DATE('2003/05/03 17:02:44', 'yyyy/mm/dd hh24:mi:ss'));
Insert into account_transaction(account_number,transactionId,created_date)values(000007,543682,TO_DATE('2003/05/03 21:02:44', 'yyyy/mm/dd hh24:mi:ss'));

我想根据以下条件检索最近交易的帐号。当我使用 card_number 作为 key 时，检查 card_number 是否与两个 account_number 相关联，如果是，请转到 account_transaction 并返回有最近 created_date 的一方。如果 card_number 有两个以上的帐户或少于两个帐户，则不要执行任何操作。

输入：

我通过 card_number= 123456 时的预期输出

当我传递其他 card_numbers 时，不会检索任何内容，因为它不符合条件

Answer 1

嗯。 . .

select ca.*
from (select ca.card_number, act.*,  -- or whatever columns you want
             row_number() over (partition by ca.card_number order by act.created_date desc) as seqnum
      from (select ca.*, count(*) over (partition by ca.card_number) as cnt
            from card_accounts ca
           ) ca join
           account_transaction act
           on act.account_number = ca.account_number
      where ca.cnt = 2
     ) ca
where seqnum = 1;

最里面的子查询计算每个数字的帐户数，where ca.cnt = 2 过滤为正好两个。中间子查询获取给定数字的最新交易。

注意：如果要过滤特定数字，可以在最里面的子查询中进行。

Here 是一个 dbfiddle。