Power Pivot Principles: The A to Z of DAX Functions – DATESMTD

In our long-established Power Pivot Principles articles, we continue our series on the A to Z of Data Analysis eXpression (DAX) functions.  This week, we look at DATESMTD.

The DATESMTD function

The DATESMTD function is one of the time intelligence functions.  It returns a set of dates for the month to date in the current context.  It operates using the following syntax:

There is only one [1] argument for the DATESMTD function:

• dates: this argument is required, and it is the name of a column or one column table containing dates.  This can be any of the following:
• a reference to a date / time column
• a table expression that returns a single column of date / time values
• a BOOLEAN expression that defines a single-column table of date / time values.

The resulting table includes only dates that exist within the dates argument.

Since the DATESMTD function is a time intelligence function, there are few key notes you should consider when using it (or any time intelligence function):

• all dates need to be present for the years required.  All the days in this span, from January 1 to December 31, must be included in the Date table.  The date table must include all dates from commencement to the last day of a fiscal year if the report solely refers to fiscal years
• a column with a DateTime or Date data type and unique values is required.  Typically, this column is known as Date.  Although it is common practice, this is not necessary when defining associations with other tables.  However, the ‘mark as Date Table’ feature should relate to the Date column, which must have distinct values
• the Date table must be designated as a date table in the model in case the relationship between the Date table and any other table is not dependent upon the Date.

Consider the following example: we have a table named Date_Table that contains dates ranging from 1 January 2020 to 15 May 2021:

Using the DATESMTD function on this table as follows will yield a table containing all of the days of the latest month within the data:

As the latest date within the data was 15 May 2021, this resulting table contains the dates of May 2021 up to the final date defined.

Come back next week for our next post on Power Pivot in the Blog section.  In the meantime, please remember we have training in Power Pivot which you can find out more about here.  If you wish to catch up on past articles in the meantime, you can find all of our Past Power Pivot blogs here.