In one of the previous “recipes” we talked about how to use the Excel GROUPBY function. On that occasion, you could find out how to use it in one of the standard scenarios of its application, and now you will learn how to use it in a slightly more advanced way. To begin with, how you can group by two or more dimensions, and then how to display percentages, determine the depth of the calculation, and so on.
If writing SQL queries is in your job description I am certain that you, in great extent, inside SELECT command, use a GROUP BY clause that allows you to group row values by a given column and then apply an aggregation function, e.g. SUM, COUNT, AVERAGE, MIN, MAX… I have good news for you: we can achieve almost the same thing within an Excel report by using the GROUPBY function…
Power Query has features that allow you to group and aggregate data in a similar way as when writing T-SQL structures, without writing a single line of code. Therefore, the process is much faster and easier. Grouping can be done by one or more report dimensions, and the order is determined in a similar manner as when sorting. Also, multiple data aggregation functions are supported as well as possibility of multiple aggregation…
The “D” functions are used for multiple data aggregation in the given table. In essence, they do the same thing as “IFS” functions in a slightly more elegant way, and whether this way is better – you estimate yourself! By the way, I am an adversary when the “experts” describe tables as databases. Sometimes the database actually makes one table, but this is very rare. Now, at least you know what letter “D” in ther prefix stands for!
Aggregation of data is a process that we’re implicitly performing every time we drag a reporting dimension in the field Values. However, when you create complex reports, it is useful to use functions for aggregation (SUM, AVERAGE, COUNT) to create measures that will be used in the report. Once thought out measures may be used as a building block to create complex DAX expressions.