sql - 通过根据两个(起始和终止)值计算非中断时间段进行分组

Question

可以使用哪种 Oracle SQL 技术来连接这些行:

id | from | to
--------------
 a |   20 | 25
 a |   26 | 30
 a |   32 | 40
 b |    1 |  5
 b |    7 | 10
 b |   11 | 20

对于这样的结果:

 a |   20 | 30
 a |   32 | 40
 b |    1 |  5
 b |    7 | 20

？假设from和to是整数周期的开始和结束，并且有必要为 id 选择不间断周期。的

只是寻找正确的方向和示例，可以使用 group by 来完成此操作吗？或connect by或者其他什么？

数据库是Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production

Answer 1

也许类似的东西:

select
    field_id,
    min(field_from),
    max(field_to)
from (
    select
        field_from,
        field_to,
        field_id,
        sum(willSum) over(partition by field_id order by field_from) as GID
    from (
        select
            field_from,
            field_to,
            field_id,
            case when field_from
                    = Lag(field_to) over(partition by field_id order by field_from)
                 then 0 else 1 end as willSum + 1
        from
            rj_mytest
        )
    )
group by
    field_id,
    GID
order by
    field_id,
    min(field_from);

还有几个类似的例子:https://forums.oracle.com/thread/969005