Introduction

DAX includes many functions that enable you to aggregate and compare data over time periods. To use the time intelligence functions, you must ensure that a table has been chosen as the date table in your model. In addition, the date table must have one row for each day in the year. In the following recipes, you will use the Calc_Date_T table created in Chapter 9, DAX Syntax and Calculations. The Crash_Date will be used as the date column. The time functions will use this date table as the basis for all of the calculations.

Date calculations can be either additive or semi-additive. Additive measures can be summed across the date dimension in relation to the fact tables. For instance, total records created by month or year. Semi-additive measures can only be summed across certain dimensions but not all, for example, the opening balance of crashes recorded in a month. If you total the opening balance of crashes for each month in the year 2015, it would not total the total number...