按聚合条件对数据进行分组

Question

I need to compose a query (one transaction) that will group elements and transform element's data into groups by sum of values with minimum sum value - 10 for example. If a value is equal to or greater of 10 it should be a separate group.

ElementId | GroupId | Value
1 | NULL | 12
2 | NULL | 10
3 | NULL | 9
4 | NULL | 13
5 | NULL | 25

GroupId | Sum
empty

Element with id 3 can be grouped with any other element, but ideally with another value that fewer than 10. Also, I need to update the relationship between elements and groups After the query execution:

ElementId | GroupId | Value
1 | 1 | 12
2 | 2 | 10
3 | 3 | 9
4 | 3 | 13
5 | 4 | 25

GroupId | Sum
1 | 12
2 | 10
3 | 22 (13 + 9)
4 | 25

Any ideas?

Answer 1

You can use analytical function (for given sample data) as follows:

Select groupid_new as groupid,
       Sum(value) as value
  From
(Select t.*,
       Sum(case when value >= 10 then value end) over (order by elementid) as groupid_new
  From your_table t) t
Group by groupid_new