Category: DAX

Shabnam Watson answers a couple of questions around aggregations and time series in Power BI:

I have received a couple of questions about Aggregations in Power BI and whether they can be used to cover time series calculations such as Year to Date, Quarter to Date, and Month To Date. The answer is yes. Since time series calculations break down into calculations over a series of days, an aggregation table defined at day level with the basic summarization methods (min, max, sum, count) and the right relationship with a Date dimension, can answer Year to Date, Quarter to Date, and Month To Date calculations.

Let’s take a quick look at one such calcualtion and how it can be covered with an aggration. I am going to use the same version of AdventureWorks sample database and Power BI model that I used in my previous blog post on aggregations, with a few changes.

Read on for a demonstration.

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Reza Rad wants to compare prior years to the current year, using year-to-date comparisons:

I have previously written about how to calculate the same period last year calculation and compare this year’s values with the last year’s values. However, sometimes, you don’t yet have the full year, especially for the current year. You might want to compare this year’s value with the last year’s value up until the same day but last year. This is what I call same period last year to date. Here in this blog article, I’ll explain how you can do that using DAX in Power BI. To learn more about Power BI, read Power BI from Rookie to Rock Star.

Click through to see how it’s done.

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Cecilia Brusatori gives us a date dimension created with DAX:

We are going to follow the steps to manually create a dimension Date table with basic DAX. First thing, we need to create a new table.

Click through for the demo. There’s a lot more you can include in a date dimension, but this gives you the starting point.

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Gilbert Quevauvilliers wants to see the specific values involved in a Power BI filter:

I was working with a customer trying to get them to better understand DAX and one if the things that is difficult to understand is how the filtering works in DAX.

The challenge I have found is that when using filters in a DAX measure I cannot visually see what is happening within the DAX Filter.

Below I will show you how I can see the values in the FILTER

Click through to see how.

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Alexander Arvidsson shows how we can concatenate columns in Power BI using DAX:

Finally we can tackle the last hurdle – the column that shows both the current number of certifications and the requested goal. Had this been Excel it would have been dead easy – we just create a new cell that concatenates two other cells like this:

Then we copy the formula to all the rows. Easy. But this is not Excel. The “goal” part is simple – that’s just another column. The trick is to count all the other rows in the table with the same key. Let’s add the key column to the table so we see what we’re working with. “CompKey” is the concatenated key we created in the previous blog post. “Number of certs” is a count of the rows in the table, and because of row context it gets evaluated per key.

Read on for the solution.

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