Oracle SQL：如何对每行的每 x 个后续行求和

Question

我有一个数据 table 看起来像这样：

|Contract Date | Settlement_Prcie |
|--------------|------------------|
| 01/10/2020   |         50       |
|--------------|------------------|
| 01/11/2020   |         10       |
|--------------|------------------|
| 01/01/2021   |         20       |
|--------------|------------------|
| 01/02/2021   |         30       |
|--------------|------------------|
| 01/03/2021   |         50       |
|--------------|------------------|

我想编写一个查询，对下面的每两行求和...例如，在合同日期为 01/10/2020 的第一行，总和列将加上 10 和 20 得到结果30. 下一行，总和列将 20 和 30 相加得到 40，依此类推。结果 table 的结果如下所示：

|Contract Date | Settlement_Prcie | Sum Column |
|--------------|------------------|------------|
| 01/10/2020   |         50       |     30
|--------------|------------------|------------|
| 01/11/2020   |         10       |     50
|--------------|------------------|------------|
| 01/01/2021   |         20       |     80
|--------------|------------------|------------|
| 01/02/2021   |         30       |
|--------------|------------------|
| 01/03/2021   |         50       |
|--------------|------------------|

任何人都可以帮助我进行查询以不仅针对 2 个后续行而且针对 x 个后续行执行此操作。

到目前为止，我已经尝试过使用 SUM (Settlement_Price) Over (order by Contract_date Rows between 3 preceding and current row) - Current row 当然不行，但那是我所能做的。

Answer 1

SUM (Settlement_Price) Over (order by Contract_date Rows between 1 following and 2 following)

Answer 2

可以使用SUM解析函数：

SELECT contract_date,
       settlement_price,
       CASE COUNT(*) OVER (
              ORDER BY contract_date ROWS BETWEEN 1 FOLLOWING AND 2 FOLLOWING
            )
       WHEN 2
       THEN SUM( settlement_price ) OVER (
              ORDER BY contract_date ROWS BETWEEN 1 FOLLOWING AND 2 FOLLOWING
            )
       END AS sum_column
FROM   table_name;

或者您可以使用 LEAD:

SELECT contract_date,
       settlement_price,
       LEAD( settlement_price, 1 , NULL ) OVER ( ORDER BY contract_date )
         + LEAD( settlement_price, 2 , NULL ) OVER ( ORDER BY contract_date )
         AS sum_column
FROM   table_name;

所以，对于测试数据：

CREATE TABLE table_name ( contract_date, settlement_price ) AS
SELECT DATE '2020-10-01', 50 FROM DUAL UNION ALL
SELECT DATE '2020-11-01', 10 FROM DUAL UNION ALL
SELECT DATE '2020-12-01', 20 FROM DUAL UNION ALL
SELECT DATE '2021-01-01', 30 FROM DUAL UNION ALL
SELECT DATE '2021-02-01', 50 FROM DUAL;

两个查询输出：

CONTRACT_DATE | SETTLEMENT_PRICE | SUM_COLUMN
:------------ | ---------------: | ---------:
01-OCT-20     |               50 |         30
01-NOV-20     |               10 |         50
01-DEC-20     |               20 |         80
01-JAN-21     |               30 |       null
01-FEB-21     |               50 |       null

db<>fiddle here

Oracle SQL：如何对每行的每 x 个后续行求和

Oracle SQL: How can I sum every x number of subsequent rows for each row

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