Forum Discussion
Recursive query
Hello,
It is possible to execute recursive query (something similar to SQL CTE recursive)? I have table with following data (there is no limit of data rows count):
| -0,5 |
| -0,5 |
| 0,25 |
| -0,5 |
My goal is to get previous row result and add to it value from current row with rule: if result < 0,5 then result= 0,5 and if result> 3 then result = 3.
So the final table should be:
| Value | Result | Previous row Result + Current row Value |
| -0,5 | 1 | Previous row is null so we take initial value '1' |
| -0,5 | 0,5 | (1 + (- 0,5)) |
| 0,25 | 0,75 | (0,5 + 0,25) |
| -0,5 | 0,5 | (0,75 + (-0,5)) |
Piece of cake for Power Query's List.Accumulate:
let Source = Table1, ResultLists = List.Accumulate(List.Skip(Source[Value]),{1},(Result,Value) => Result & {List.Min({3,List.Max({0.5,List.Last(Result) + Value})})}), TableFromColumns = Table.FromColumns({Source[Value],ResultLists},type table[Value = number, Result = number]) in TableFromColumnsI share the doubt regarding the first result: according to the information provided, it should be 1, regardless of the first value.
I would expect some initial value (e.g. 1.5) and the first result would be that initial value plus the first value (1.5 - 0.5 = 1), not lower than 0.5 and not higher than 3.0.
Anyhow the code is based on the information provided, so the first value is skipped.
A screenshot with the result from a larger sample:
6 Replies
yes you will find many examples of running totals. the arbitrary rule of starting with 1 is the only twist that I see.
It's not that easy I think. I need to calculate value of Result column based on previous row Result column value. That's why recursion could be proper solution, but I dont't know if it's possible with Power BI.
Piece of cake for Power Query's List.Accumulate:
let Source = Table1, ResultLists = List.Accumulate(List.Skip(Source[Value]),{1},(Result,Value) => Result & {List.Min({3,List.Max({0.5,List.Last(Result) + Value})})}), TableFromColumns = Table.FromColumns({Source[Value],ResultLists},type table[Value = number, Result = number]) in TableFromColumnsI share the doubt regarding the first result: according to the information provided, it should be 1, regardless of the first value.
I would expect some initial value (e.g. 1.5) and the first result would be that initial value plus the first value (1.5 - 0.5 = 1), not lower than 0.5 and not higher than 3.0.
Anyhow the code is based on the information provided, so the first value is skipped.
A screenshot with the result from a larger sample:
Hi there,
I just want to do a very simple loop a list and each of loop add a column to table; after many seacrh and test , still don't know how to do it. Could you give a simple example? Thank you very much.
