In Power BI, you can avoid a many-to-many relationship by creating a bridge table or by using DAX formulas.
Bridge Table Approach:
One way to handle a many-to-many relationship is by creating a bridge table that sits between the two tables with the many-to-many relationship. The bridge table connects the two tables through one or more intermediate tables that have a one-to-many or many-to-one relationship with the original tables. This allows you to break down the many-to-many relationship into multiple one-to-many relationships.
Let’s consider an example to understand this approach. Suppose we have two tables: “Products” and “Orders”. Each product can have multiple orders, and each order can include multiple products. Instead of directly connecting these tables, create a bridge table called “Product_Order” which contains the primary key columns from both tables. Now, you can establish a one-to-many relationship between “Products” and “Product_Order”, as well as between “Product_Order” and “Orders”. This way, you avoid the many-to-many relationship between “Products” and “Orders”.
DAX Formula Approach:
Another way to handle a many-to-many relationship is by using DAX formulas to create a calculated table or calculated columns. You can use functions like CONCATENATEX, SUMMARIZECOLUMNS, or VALUES to aggregate or filter data based on specific criteria.
Let’s continue with the above example. Instead of creating a bridge table, you can use DAX formulas to aggregate or filter data. For example, you can create a calculated table or column to calculate the total quantity of products ordered for each order. This way, you can avoid the many-to-many relationship between “Products” and “Orders” and have a more simplified relationship structure.