WEEKDAY Function (DAX)
Returns a number from 1 to 7 identifying the day of the week of a date. By default the day ranges from 1 (Sunday) to 7 (Saturday).
A date in datetime format.
Dates should be entered by using the DATE function, by using expressions that result in a date, or as the result of other formulas.
A number that determines the return value:
An integer number from 1 to 7.
In contrast to Microsoft Excel, which stores dates as serial numbers, DAX works with dates and times in a datetime format. If you need to display dates as serial numbers, you can use the formatting options in Excel.
You can also type dates in an accepted text representation of a date, but to avoid unexpected results, it is best to convert the text date to a datetime format first.
When the date argument is a text representation of the date, the function uses the locale and date/time settings of the client computer to understand the text value in order to perform the conversion. If the current date/time settings represent dates in the format of Month/Day/Year, then the string, "1/8/2009", is interpreted as a datetime value equivalent to January 8th of 2009. However, if the current date/time settings represent dates in the format of Day/Month/Year, then the same string would be interpreted as a datetime value equivalent to August 1st of 2009.
The following example gets the date from the [HireDate] column, adds 1, and displays the weekday corresponding to that date. Because the return_type argument has been omitted, the default format is used, in which 1 is Sunday and 7 is Saturday. If the result is 4, the day would be Wednesday.