When creating anextended tablein ServiceNow, itinherits all fieldsfrom thebase table, meaning you donotneed to recreate those fields. Instead, you only need to define fields that are:
Not present in the base table– If a fielddoes not existin the base table but is required for the extended table, it must be created.
Specific to the extended table– Custom fields that are unique to the child table need to be added.
A. The mandatory fields for the base table– Since the extended table inherits the base table’s fields, mandatory fields from the base table are already included automatically.
B. The reference fields for the base table– Reference fields are not always required unless they are specific to the extended table’s functionality.
If you extend theTasktable to create aCustom Tasktable, the new table automatically gets allTask fields(likeNumber,Short Description, etc.).
If you want to add a new field, such asCustom Priority, you need to create it manually.
ServiceNow Extending Tables
ServiceNow CSA Training Module:"Data Schema and Extending Tables"
Why Other Answers Are Incorrect:Example Scenario:References from Certified System Administrator (CSA) Official Documentation: