The SQL language offers the following types of JOIN:
- INNER JOIN
- OUTER JOIN
- CROSS JOIN
The result of a JOIN does not depends on the presence of a relationship in the data model. You can use any column of a table in a JOIN condition.
In DAX there are two ways you can obtain a JOIN behavior. First, you can leverage existing relationships in the data model in order to query data included in different tables, just as you wrote the corresponding JOIN conditions in the DAX query. Second, you can write DAX expressions producing a result equivalent to certain types of JOIN. In any case, not all the JOIN operations available in SQL are supported in DAX.
Read on for several examples.