Measures versus calculated columns

After showing you the basic aggregation functions in DAX, it’s important to know that this language is used for creating measures and calculated columns. Unlike Excel, where adding a column to a table is simply done by right-clicking and adding the column to the left or right, in Power BI, it’s a bit different. Here, we have to specify the expression that will define the column, and this expression must be written in DAX.

A calculated column is essentially an additional column that’s added to a table that you can use in the same way as other columns in your model. You can use aggregation functions on them and even use them to create relationships with other tables. The DAX expression you define for this column will be executed on the current row, row by row. This means you can’t directly access values from other rows like in Excel, unless you modify the filter context. The topic of filter contexts is something we’...