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## Select Value from row before

Hello to everybody,

I have a question for calculating in PowerQuery with the value of the row before.

I have a list with movements of goods in a warehouse.

Because there a of couse some goods with more than one movement I want to calculate the value for this good referring to the value before the movement.

As an example:

Date                     stock per date                Article                 kind of movement(+ for orders                                 quantity

/- for taking material to production)

01.01.2022            10                                123456                         -                                                                               5                          02.01.2022              5                                 123456                        -                                                                               4

03.01.2022              1                                 123456                        +                                                                            15

03.01.2022            16                                 123456                        -                                                                                5

Amd so on... Is there a posibility to solve this problem?

I alredy added a colum with an index and an second colum with an index +1. So I can merge the table with itsself an I can check if the value of the colum for the arcitle in the row before is the same value in the actual row. So far, so nice. But now I am not flexbile enough with my code and not far enough with my knowledge of writing formulas in M. How can I calculate the current value with the value before?

In Excel so far it is possible for me, but I would like to do it in Query, because doing it in Excel after refreshing the data not all colums are filled with the formula I use in Excel.

4 REPLIES 4
Anonymous
Not applicable

Good morning,

thx for your fast replies. Maybe it will be easier to understand if I upload some screenshots from the data I use.

Because I decrease the column width, I will first explain what is in the colums.

Colum1: project number of cumstomer

Colum2: date of warehouse movement

Colum3: article code

Colum9: stock of arcticle before movement

Colum10: quantity of momement (- for taking material to production)

Colum11: stock after movement

Rest of colum is for my promblem not needed, but is needed for the presentation of the result.

I tried this code as a solution for my problem:

If there is just one movement for an article this code is useful, but with two or more movements not. (s. Screenshot) I get an error, for article with more movements. Value can't be converted in a list.

I also had a look at this solution:

Solved: Re: Power Query/Power Pivot - Dynamically Calculat... - Microsoft Power BI Community

But to be honest: I didn't understand the code. 😞

Memorable Member

Hi @Anonymous

The straightforward solution to your code (Table.AddColumn(#"addcolum", "Benutzerdefiniert", each if [Häufigkeit]="Doppelt" then ([colum11]{-1}+[colum10]) else [colum10]).) is below. I've added some comments in the code, which hopefully make sense.

``````let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjQwMDC2VNJRcs1MS0zOADIMDcz1jCzNgCxdQz0DI7CImZ6RuZlSrA6Sepf8goLUnBIiNJhYGJkiW2AExSao8ggDQZK6BnrGIFFDPTNTpdhYAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Atricle = _t, Häufigkeit = _t, colum9 = _t, colum10 = _t, colum11 = _t]),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"colum9", type number}, {"colum10", type number}, {"colum11", type number}}),

// Code in the next line is iterating through all rows in the table applying the test and it test is satisfied we take a previous line [stored as last item in a] via List.Last(a)
// and then add it to colum10, otherwise [if the test fails] we take colum10 only
Calculate = List.Accumulate(Table.ToRecords(#"Changed Type"), {}, (a,n)=> a & {Record.AddField(n, "Benutzerdefiniert", if n[Häufigkeit]="Doppelt" then (List.Last(a)[colum11]+n[colum10]) else n[colum10])} ),

//converting the list of records which we made on the previous step back to a table using value.type to format the table
BackToTable = Table.FromRecords(Calculate, Value.Type(Table.AddColumn(#"Changed Type", "Benutzerdefiniert", each null, type number)))
in
BackToTable``````

But I do not understand the meaning of the column [Benutzerdefiniert] that you create. May be there is someting wrong with the formula? Did you mean to use else coum11 instead of colum10? Anyway, it should be easy to sort out. AAs you can see, I pretty much just using a straight copy paste of your formula, just refereing it to List.Last rather than {-1}.

Cheers,

John

Memorable Member

Hi @CARL12345,

Would this be something similar to this post?

Solved: Re: Power Query/Power Pivot - Dynamically Calculat... - Microsoft Power BI Community

Cheers,

John

Impactful Individual

Hi @CARL12345 ,

I don't seem to be able to see \$value in the provided example.

Let me know if it helps with your case. O

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