Add a many-to-many relationship

To design a many-to-many relationship between two tables, create a junction table to link them together.

Create the junction table using the primary key from each table.

Example

Table_A has a primary key column named Column_A.

Table_B has a primary key column named Column_B.

Figure: Initial tables, each with a primary key defined

Diagram of the two tables described as Table_A and Table_B.

To create the many-to-many relationship, add a junction table. This table is comprised of the primary key columns from each of the other tables.

Figure: Create and include the junction table

Diagram of the junction table added to diagram, along with the foreign key relationships.