递归 PL SQL 查询帮助

Question

我有一张两张桌子。我想从这两个表中得到以下结果。任何帮助表示赞赏。

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事件表

event_id | gross_amount | transaction_id
1        | 10           | 1
2        | 12           | 5

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事务表

trx_id | debit | credit | link_trx_id
1      | 4     | 0      | null
2      | 0     | 2      | 1
3      | 0     | 1      | 2
4      | 3     | 0      | 3
5      | 0     | 5      | null
6      | 0     | 3      | 5

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预期结果：

trx_id | debit | credit | current_gross | current_net
1      | 4     | 0      | 10            | 6
2      | 0     | 2      | 6             | 8
3      | 0     | 1      | 8             | 9
4      | 3     | 0      | 9             | 6
5      | 0     | 5      | 10            | 15
6      | 0     | 3      | 15            | 18

说明

如您所见，事务 1,2,3,4 落入一组，而 4,6 落入另一组。对于每笔交易都需要将其链接到以前的交易 current_net 作为它的 current_gross。

获取 current_gross 基本上是一个递归调用。这里我不能使用 PL SQL 函数，我可以编写一个快速递归函数来计算 current_gross。我需要这个任务的纯 PL/SQL 查询。 (可以使用内置的PL SQL函数)

Answer 1

这是一个未经测试的近似答案（如果您为您的数据/结构提供了 create table 和 insert 语句，我会对其进行测试）。它假定您的事务表中没有分支（也就是说，link_trx_id 是唯一的）。基本上，我们使用递归连接来获取分组、父信息和顺序，然后使用分析函数来获取运行总计 (current_net)。与其尝试获取以前的总数（我们可以这样做），不如简单地从current_net 中删除当前行的credit 和debit 似乎更有意义。

SELECT trx_id,
       debit,
       credit,
       root_amt - cum_debit + cum_credit + debit - credit AS current_gross,
       root_amt - cum_debit + cum_credit AS current_net
FROM   (SELECT trx_id,
               debit,
               credit,
               SUM(credit) OVER (PARTITION BY event_id ORDER BY lvl) AS cum_credit,
               SUM(debit) OVER (PARTITION BY event_id ORDER BY lvl) AS cum_debit,
               root_amt
        FROM   (SELECT     trx_id,
                           debit,
                           credit,
                           LEVEL AS lvl,
                           CONNECT_BY_ROOT (gross_amount) AS root_amt,
                           CONNECT_BY_ROOT (event_id) AS event_id
                FROM       transaction t LEFT OUTER JOIN event e ON t.trx_id = e.transaction_id
                CONNECT BY link_trx_id = PRIOR trx_id
                START WITH link_trx_id IS NULL))

Answer 2

使用 Allan 的查询，我添加了创建表和插入。 该查询的变量不匹配，因此我也更正了这些变量（debit_cum/credit_cum 与子查询中的 cum-credit/cum_debit 变量不匹配）。

create table event
(event_id   number(9),
 gross_amount number(9),
 transaction_id number(9));

 insert into event values (1,10,1);
 insert into event values (2,12,5);

 create table transaction
 (trx_id number(9),
  debit  number(9),
  credit number(9),
  link_trx_id number(9)
  );

  insert into transaction values (1,4,0,null);
  insert into transaction values (2,0,2,1);
  insert into transaction values (3,0,1,2);
  insert into transaction values (4,3,0,3);
  insert into transaction values (5,0,5,null);
  insert into transaction values (6,0,3,5);



SELECT trx_id,
       debit,
       credit,
       root_amt - debit_cum + credit_cum + debit - credit AS current_gross,
       root_amt - debit_cum + credit_cum AS current_net
FROM   (SELECT trx_id,
               debit,
               credit,
               SUM(credit) OVER (PARTITION BY event_id ORDER BY lvl) AS credit_cum,
               SUM(debit) OVER (PARTITION BY event_id ORDER BY lvl) AS debit_cum,
               root_amt,
               event_id
        FROM   (SELECT     trx_id,
                           debit,
                           credit,
                           LEVEL AS lvl,
                           CONNECT_BY_ROOT (gross_amount) AS root_amt,
                           CONNECT_BY_ROOT (event_id) AS event_id
                FROM       transaction t LEFT OUTER JOIN event e ON t.trx_id = e.transaction_id
                CONNECT BY link_trx_id = PRIOR trx_id
                START WITH link_trx_id IS NULL));