Relationships in Power BI Data Models are always defined between a single column from each of the two tables. One of these two columns must uniquely identify the rows of its table, such as the Currency Key column from the Currency table in the Fact-to-dimension relationships section earlier in this chapter. Power BI will throw an error message if a row with a duplicate value for the relationship column is attempted to be loaded to the one side of the relationship, as shown in the following screenshot:
Uniqueness enforced in relationships
Power BI and SSAS Tabular models do not enforce or require referential integrity as with relationship ...
