Database Schema and Tables Flashcards

In ServiceNow, what does the 'sys_id' field represent in every table?

Answer: A globally unique 32-character hexadecimal identifier

The sys_id is a 32-character GUID (globally unique identifier) automatically assigned to every record in every ServiceNow table.

Which ServiceNow table stores all table definitions and metadata about tables themselves?

Answer: sys_db_object

The sys_db_object table stores metadata about all tables defined in the ServiceNow instance, including table name, label, and parent.

What is the purpose of the 'sys_dictionary' table in ServiceNow?

Answer: It defines field-level metadata such as type, max length, and attributes for each column

The sys_dictionary table contains one row per field per table, storing the field's data type, length, default value, and other attributes.

When you extend a table in ServiceNow, records in the child table are stored:

Answer: In both the parent and child tables, with sys_id linking them

ServiceNow uses table inheritance where a child record has a row in the parent table (for inherited fields) and a row in the child table (for extended fields), joined by sys_id.

Which field type should you choose in ServiceNow when you need to store a reference to another record in a different table?

Answer: Reference

The Reference field type stores the sys_id of a record in a specified target table and displays the record's display value.

What does the 'sys_class_name' field indicate on a record in a table hierarchy?

Answer: The actual table (class) the record belongs to within the inheritance hierarchy

sys_class_name stores the specific extended table name the record belongs to, allowing ServiceNow to reconstruct the full record from the hierarchy.

In ServiceNow, a 'Many-to-Many' relationship between two tables is typically implemented using:

Answer: Both B and C are valid approaches

ServiceNow supports M2M relationships via Glide List fields (which store multiple sys_ids) or via explicit junction tables; both are valid, with junction tables preferred for richer relationship data.