DAX Function Guide

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.

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.