Many-to-many relationships in ServiceNow

Many-to-many (M2M) relationships are similar to one-to-many relationships, except that they aren't usually dependent on a foreign key column in a child table. Instead, many-to-many relationships in ServiceNow usually rely on an intermediary table called an M2M table. This table commonly has a PK (Sys ID) of its own for each record, and otherwise primarily consists (other than the default System fields, like Updated and Created by) of two FK columns.

As it happens, we've already seen one example of a many-to-many table: the Lou's Shoes Order table we defined earlier! This table creates a many-to-many relationship between the Customer and Item tables. This structure makes sense, because any one customer might order multiple different items, and any one item might be purchased by multiple different customers.

Luckily, in ServiceNow, there is an easy and pre-defined way to create M2M tables. Follow the following steps, to see how to define a new many-to-many relationship table, and add a related list to display that relationship on both related tables (as opposed to just the parent records).