在sybase中重建窗口函数row_number

Question

如果我在 Sybase 中有可用的窗口函数，我可以轻松解决一个问题，但我没有：

考虑一个表test：

+------------+----------------+-------------+
| Account_Id | Transaction_Id | CaptureDate |
+------------+----------------+-------------+
| 1          | 1              | 2014-01-01  |
| 1          | 2              | 2013-12-31  |
| 1          | 3              | 2015-07-20  |
| 2          | 1              | 2012-02-20  |
| 2          | 2              | 2010-01-10  |
| ...        | ...            | ...         |
+------------+----------------+-------------+

我想为每个帐户获取一个结果集，其中包含最新的CaptureDate 和对应的Transaction_Id。使用窗口函数row_number 这很容易：

select Accounts_Id, CaptureDate, Transaction_Id from 
    (select 
    CallAccounts_Id,
    CaptureDate,
    Transaction_Id,
    ROW_NUMBER() OVER(partition by Accounts_Id order by CaptureDate desc) row
    from test) tbl
where tbl.row = 1

但是我的sybase 版本没有这个。很明显，喜欢……

select max(Transaction_Id ), max(Transaction_Id ), Account_Id 
from test
group by Account_Id 

不起作用，因为它并不总是给我正确的 Transaction_Id。 我怎样才能在 Sybase 中做到这一点而不让它变得非常冗长？

谢谢！

Answer 1

试试下面：

SELECT  Account_Id, Transaction_Id, CaptureDate
FROM    test a
WHERE   CaptureDate =   (
                        SELECT  MAX(CaptureDate)
                        FROM    test b
                        WHERE   a.Account_Id = b.Account_Id
                    )

编辑 1： Duplicate CaptureDate 不在您的示例中，因此我没有处理这种情况。试试下面：

SELECT  Account_Id, Transaction_Id, CaptureDate
FROM    test a
WHERE   CaptureDate =   (
                        SELECT  MAX(CaptureDate)
                        FROM    test b
                        WHERE   a.Account_Id = b.Account_Id
                    )
AND     Transaction_Id =
                    (
                        SELECT  MAX(Transaction_Id)
                        FROM    test c
                        WHERE   a.Account_Id  = c.Account_Id
                        AND     a.CaptureDate = c.CaptureDate
                    )