Returns a related value from another table.
The column that contains the desired value.
A single value that is related to the current row.
The RELATED function requires that a relationship exists between the current table and the table with related information. The argument specifies a column reference, and the function follows a chain of one or more many-to-one relationships to fetch the value from the specified column in the related table. If a relationship does not exist, RELATED raises an error.
The RELATED function needs a row context; therefore, it can only be used in calculated column expression, where the current row context is unambiguous, or as a nested function in an expression that uses a table scanning function. A table scanning function, such as SUMX, gets the value of the current row value and then scans another table for instances of that value.
Learn more about RELATED in the following articles:
Other related functions are:
Contributors: Alberto Ferrari, Marco Russo
MSDN documentation: https://docs.microsoft.com/en-us/dax/related-function-dax