Update Historical Table with Daily Data in Power Query

[Anonymous]

I start this exercice having two tables with the same Columns (ID, Offer, Price & Total Views). One of them acts as my Historical data, the second one is a daily update that I use to feed the first one. Both in Excel format.

In orther to do this, I run a JoinKind RightAnti to check first new items that later on I append into my Historical table. Now I would like to update the columns Offer & Price in case they have changed, so I use JoinKind RightAnti selecting ID & Offer to identify those rows (same operation for Price column). My first question is, how do I replace the values of the Historical Offer & Price columns with the Daily data I have obtained? When that, How can I create and if statement to add a new column and fill a cell in the same row with today's date in my Hitorical Table due to the status update? Also, Total Views column will be replace daily.

The final result will be my Historical Table having ID, Offer, Price, Date & Total Views columns. Is there any way to get it done inside power query? Please, any help would be much appreciated. Regards

[dax · Accepted solution]

Hi @Anonymous ,

You could refer to below M code yo see whether it work or not.

let
    Source = Table.NestedJoin(history, {"id"}, daily, {"id"}, "daily", JoinKind.LeftOuter),
    #"Expanded daily" = Table.ExpandTableColumn(Source, "daily", {"price", "view"}, {"daily.price", "daily.view"}),
    Custom1 = Table.ReplaceValue(#"Expanded daily",each [price], each if [price]=[daily.price] or [daily.price]=null then [price] else [daily.price], Replacer.ReplaceValue, {"price"}),
    Custom2 = Table.ReplaceValue(#"Custom1",each [view], each if [view]=[daily.view] or [daily.view]=null then [view] else [daily.view], Replacer.ReplaceValue, {"view"}),
    Custom3 = Table.ReplaceValue(#"Expanded daily",each [daily.view], each if [view]=[daily.view] and [price]=[daily.price] or [daily.view]=null then null else DateTime.LocalNow(), Replacer.ReplaceValue, {"daily.view"}),
    #"Removed Columns" = Table.RemoveColumns(Custom3,{"daily.price"})
in
    #"Removed Columns"

 In addition, if the date column in daily table, you could change code like below(you also need to exapnd this column in table)

Custom3 = Table.ReplaceValue(#"Expanded daily",each [daily.view], each if [view]=[daily.view] and [price]=[daily.price] or [daily.view]=null then null else [daily.date], Replacer.ReplaceValue, {"daily.view"})

Best Regards,
Zoe Zhi

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[Anonymous]

Wow! It hepls me to sort my code out! Thanks a lot Zoe.