PowerPivot and Analysis Services 2012 Tabular do not support many-to-many (M2M) relationship directly in the data model. However, you can obtain the desired result from a many-to-many relationship by writing a DAX expression. For example, consider the classical M2M relationship between bank accounts and customers.
SQL Server Analysis Services introduced modeling many-to-many relationships between dimensions in version 2005. At a first glance, we may tend to underestimate the importance of this feature: after all, many other OLAP engines do not offer many-to-many relationships. Yet, this lack did not limit their adoption and, apparently, only a