A Many-to-Many Relationship is a relational structure comprised of two separate one-to-many relationships connected by a Join Table (Intermediate table) that allows two tables to act as though they are both master and details tables, allowing records from either table to be a parent to the other table’s records.

NOTE: Throughout this article, we will be using the example of Students and Classes to help illustrate a Many-to-Many Relationship. If you’d like, follow along in Quickbase by creating a students and classes table.

In theory, students can have many classes, and classes can have many students. There is a correct and incorrect way of creating this relationship. The upcoming examples will illustrate both methods:

The Wrong Way to Handle a Many-to-Many Method

In this example, you can see that both students and classes are related to one another and represent information passing to each other similar to how cars move on a two-lane highway.

Ultimately, this method is not ideal and creates duplication of work in Quickbase.

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The Right Way to Handle a Many-to-Many Method

In this example, we have created a Join Table. It’s a third table that helps connect data from the two tables you are trying to connect.
To help further illustrate, our students and classes table both contain lists of information.
The join table allows us to take the information from both the students and classes tables and create every combination of classes to students or students to classes with that information.

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BEST PRACTICE: When creating a join table, it’s best practice to name the join table something that relates to both tables connected to it.

For example, our join table for students and classes could be called “Registrations” or “Assignments.”

How to Create a Many-to-Many Relationship in Quickbase?

Create a new table to serve as the join table.

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You will want to add a new table to your application and provide an appropriate name.

Create a relationship between the new table and the existing tables.

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In our example, we created a One-to-Many Relationship between Classes and Registrations (above) and a One-to-Many Relationship between Students and Registrations (below).