Readers with knowledge of SQL know that the join operation is widespread in SQL queries, as it is the standard way to combine data stored in different tables. It is however uncommon to explicitly join tables in DAX because the relationships in the data model provide enough information to allow many DAX functions to work without an explicit join operation. Most of the time, the join between tables is implicit and automatic.
However, DAX has two explicit join functions: NATURALLEFTOUTERJOIN and NATURALINNERJOIN. Apparently, these functions correspond to the behavior of LEFT OUTER JOIN and INNER JOIN in SQL. However, they differ from SQL in how you specify the join condition. This article shows how these functions can be used in DAX with practical examples. If you need a more introductory article about the syntax of these functions, read From SQL to DAX: Joining Tables, where we compare the SQL syntax with similar DAX functions.
Click through to learn more about how these functions work and what their limitations are.