ServiceNow CSA free question 7 / 10 · Domain 5: Database Management and Platform Security
An administrator is designing a child table that shares fields with an existing parent table. Which statement about extending tables is correct?
- A table can be extended only while it is being created
- The Task table is the one allowed parent of an extension
- Extending a table moves the parent records into the child
- A table can be changed into an extension later on
Show the answer and explanation
Answer: A
Why this is correct
The documentation says administrators and application developers can only extend tables during table creation. Extension lets one or more child tables share fields and records with a parent table. A table that extends another is called a child class, and the table it extends is the parent class.
Why the other options are wrong
"A table can be changed into an extension later on" … The page limits extension to the moment the table is created. An existing table cannot be turned into an extension afterward.
"Extending a table moves the parent records into the child" … Records are not moved. The child shares fields and records with the parent; in the table per hierarchy model the parent table stores the records of the whole hierarchy.
"The Task table is the one allowed parent of an extension" … Task is one example, not the only parent. The page also lists Configuration Item [cmdb_ci], which is extended by Application, Computer, and Database.
Key point
Because extension cannot be added later, decide during design whether a new table should extend an existing one. Extending a table links the new table to the extended table, creates system fields, and creates the database tables that the selected extension model requires.
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