Definition of a SQL view — evaluate the statement:\n“A SQL view is a virtual table constructed from other tables or views.” Choose the best evaluation.

Difficulty: Easy

Correct Answer: Correct

Explanation:


Introduction / Context:
Views are pervasive in database development, used for security, abstraction, and reuse. This question asks whether a view can be described as a virtual table built from other tables or views. It checks your grasp of the conceptual model rather than performance specifics.



Given Data / Assumptions:

  • We discuss standard virtual views created with CREATE VIEW AS SELECT ...
  • Materialized or indexed views are a separate optimization feature in some systems.
  • The phrase “constructed from other tables or views” refers to the underlying SELECT query.


Concept / Approach:
A view presents the result of a stored query as if it were a table. The engine evaluates the view definition (often by query rewrite) against base tables or even other views. Thus, describing a view as a “virtual table constructed from other tables or views” is accurate. Whether it is updatable or materialized does not change that fundamental definition; those are properties or implementations layered on top.



Step-by-Step Solution:

Identify view creation: CREATE VIEW v AS SELECT ... FROM base1 JOIN base2 ...Interpret “virtual table”: projection of a query’s columns exposed as table-like schema.Conclude: statement correctly characterizes what a view is.Note: materialization is optional and vendor-dependent.


Verification / Alternative check:
Querying a view with SELECT * FROM v behaves like querying a table; dropping referenced tables invalidates the view, showing its dependence on other objects.



Why Other Options Are Wrong:

  • Updatability and materialization are orthogonal to being a view.
  • Execution plans vary but do not redefine what a view is.


Common Pitfalls:
Believing views always store data; conflating materialized views with standard views; assuming views must be updatable.



Final Answer:
Correct

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