One-to-many relationships are one type of parent-child relationship. They consist of one parent record, that is linked to many child records. This linkage is done using database table keys.

As we briefly mentioned in a previous chapter, records have a primary key (PK), and a foreign key (FK) column; though they aren't called that in ServiceNow. The PK in ServiceNow is the Sys ID [sys_id] column. Every record in ServiceNow has a Sys ID that is typically unique within the entire database (though technically a primary key only needs to be unique within a table). An example of an FK column, is any column which is meant to hold the PK of another record. These fields are reference fields in ServiceNow. The Incident [incident] table for example, contains an FK column with the label Assigned to, and an actual column name of assigned_to. This is a reference field that points to the User [sys_user] table, and contains the PK (Sys ID) of one of the records in...