解析函数窗口子句

Question

VAL 列是从 1 到 3 的数字列表，其他列应该显示：

A) 所有低于 VAL
B) 所有低于 VAL
C) 所有大于 VAL
D) 所有更大的最大值值比 VAL

我希望得到这样的结果：

V   A   B   C   D
-------------------
1 |   |   | 2 | 3
2 | 1 | 1 | 3 | 3
3 | 1 | 2 |   |

但我得到的结果是：

V   A   B   C   D
-------------------
1 |   |   | 2 | 3
2 |   |   |   |  
3 |   |   |   |

(*) 所有空白单元格均为 NULL 结果

我写的查询：

WITH T AS
       (SELECT     CAST(LEVEL AS NUMBER) val
        FROM       DUAL
        CONNECT BY LEVEL < 4)
SELECT   val
        ,MIN(val) OVER(ORDER BY val RANGE BETWEEN UNBOUNDED PRECEDING AND val PRECEDING) A --MIN_PRECEDING
        ,MAX(val) OVER(ORDER BY val RANGE BETWEEN UNBOUNDED PRECEDING AND val PRECEDING) B --MAX_PRECEDING
        ,MIN(val) OVER(ORDER BY val RANGE BETWEEN val FOLLOWING AND UNBOUNDED FOLLOWING) C --MIN_FOLLOWING
        ,MAX(val) OVER(ORDER BY val RANGE BETWEEN val FOLLOWING AND UNBOUNDED FOLLOWING) D --MAX_FOLLOWING
FROM     T
WHERE    val IS NOT NULL
ORDER BY 1
/

有人看出这个查询有什么问题吗？

提前致谢！

Answer 1

错误在 val preceding 和 val following 中。应该是 1 preceding 和 1 following.

你在那里指定的数字是相对于当前记录的，对应于 val 的记录（在给定的 window 顺序中），所以如果你指定 val 你会返回（或超前）太远了。您应该需要在当前记录之前（或之后）获得最多 min/max 一条记录。

所以：

WITH T AS
       (SELECT     CAST(LEVEL AS NUMBER) val
        FROM       DUAL
        CONNECT BY LEVEL < 4)
SELECT   val
        ,MIN(val) OVER(ORDER BY val RANGE BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING) A
        ,MAX(val) OVER(ORDER BY val RANGE BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING) B
        ,MIN(val) OVER(ORDER BY val RANGE BETWEEN 1 FOLLOWING AND UNBOUNDED FOLLOWING) C
        ,MAX(val) OVER(ORDER BY val RANGE BETWEEN 1 FOLLOWING AND UNBOUNDED FOLLOWING) D
FROM     T
WHERE    val IS NOT NULL
ORDER BY 1
/

解析函数窗口子句

Analytic function windowing clause

oracle

analytic-functions