if-then-else on comparing data from the previous field/record

[Joop]

Hi Community! I have an question on how to mimic an Excel if-then-else formula in Power BI. I don't want to use the function in the Excel base table, as I want to let PowerBI do all the work and calculations.

See here an example: I want to assign a certain value to the column "aantal", based in a comparison in the column "DatumTijdTee" of the current and the previous row value. Hope the picture explains better:

Is this a simple function, or do I have to create complicated DAX expressions?

Thanks for your help!

[Joop]

<Hello Marcel,

thanks for the solution, especially the video. This helped me very much with my question!

Cheers, Joop

[MarcelBeug · Accepted solution]

It can also be done in Power Query (M).

Code will be most efficient when you have the relevant current and previous values in 1 row.

This can be done by adding 2 index columns (1 starting with 0 and the other starting with 1) and then merge the table with itself.

An example in this video I created yesterday as an answer to a similar case.