Returns a one column table that contains the distinct (unique) values in a column, for a column argument. Or multiple columns with distinct (unique) combination of values, for a table expression argument.
The column (or table expression) from which unique values (or combination of values) are to be returned.
A column of unique values if the parameter is a single column. If the parameter is a table expression, the result has the same columns and remove only duplicated rows.
If the parameter is a single table, the result of DISTINCT is affected by the current filter context. In this case it is important to understand the differences with VALUES, which might add an additional blank row in certain conditions.
If the parameter is a table expression, DISTINCT returns a table by removing duplicate rows provided by the table expression.
Learn more about DISTINCT in the following articles:
Difference between DISTINCT and VALUES in DAX
This short post describes the differences between DISTINCT and VALUES. » Read more
Blank row in DAX
There are two functions in DAX that return the list of values of a column: VALUES and DISTINCT. This article describes the difference between the two, explaining the details of the blank row added to tables for invalid relationships. » Read more
Analyzing the performance of DISTINCTCOUNT in DAX
This article describes how to analyze the performance of a DAX measure based on a DISTINCTCOUNT calculation and how to evaluate possible optimizations. » Read more
From SQL to DAX: Projection
This article describes projection functions and techniques in DAX, showing the differences between SELECTCOLUMNS, ADDCOLUMNS, and SUMMARIZE. » Read more
Other related functions are:
Contributors: Alberto Ferrari, Marco Russo, Gerald Artman
MSDN documentation: https://docs.microsoft.com/en-us/dax/distinct-function-dax