In Oracle Database, which value-prefixes can be referenced inside row-level triggers to access the old and new row values?

Introduction / Context:
Oracle Database supports row-level triggers that fire for each affected row during INSERT, UPDATE, or DELETE operations. Inside these triggers, Oracle exposes special pseudo-records to read or assign column values. Knowing which prefixes are available is essential for correct trigger logic.

Given Data / Assumptions:

• The question concerns Oracle row-level trigger syntax.
• Available prefixes may include :new and :old to reference column values.
• We assume standard Oracle PL/SQL trigger behavior.

Concept / Approach:
:new refers to the new column values (after change) and :old refers to the original column values (before change). Their availability depends on the DML operation: INSERT provides :new, DELETE provides :old, and UPDATE provides both.

Step-by-Step Solution:

Verification / Alternative check:
Oracle PL/SQL documentation consistently demonstrates :new and :old usage within row-level triggers for all three DML events.

Why Other Options Are Wrong:
:new only and :old only are each incomplete because availability depends on the DML statement.
Neither :new nor :old is false since Oracle exposes these pseudo-records in row-level triggers.

Common Pitfalls:
Trying to assign to :old in UPDATE/INSERT triggers (not allowed). Also, attempting to reference :new in DELETE triggers or :old in INSERT triggers will fail.

Final Answer:
Both :new and :old