Power Pivot Principles: The A to Z of DAX Functions – DAY
21 March 2023
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 DAY.
The DAY function
The DAY function is one of the date and time functions. It returns a number from one  to 31 representing the day of the month. Its syntax is as follows:
It has one  argument:
- date: this argument is required, and it is a date in date time format or a text representation of a date.
If the argument is a string, it is translated into a datetime value using the same rules applied by the DATEVALUE function.
Consider the following example, where we will obtain the day from a date column. We have the following data (not displayed in full):
We can write the following DAX query to add a column to this data containing the day of the month from the column OrderDate:
This DAX query will append a column named “Sales Day” to the end of the table containing the date of the month:
But wait, there’s more. Consider the following example where we extract the day from a date represented as text. We can write the following DAX query:
The DAX query above stores the string date of “16/03/2020” into the variable StringDate. We can then use the DAY function to extract the day from StringDate. This will return the following value:
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