DISTINCTCOUNT Function (DAX)
The DISTINCTCOUNT function counts the number of different cells in a column of numbers.
The column that contains the numbers to be counted
The number of distinct values in column.
The only argument allowed to this function is a column. You can use columns containing any type of data. When the function finds no rows to count, it returns a BLANK, otherwise it returns the count of distinct values.
The following example shows how to count the number of distinct sales orders in the column ResellerSales_USD[SalesOrderNumber].