Updates to Single-Table Views

• Selection-based views: INSERT, DELETE are mapped directly to the base relation.

• Projection-based views: view must include all fields of base relation that disallow null; base table insertion is padded with nulls.

• Aggregate views: not updateable.

CREATE VIEW YearAvg AS

SELECT S.year, AVG (S.gpa)

FROM Students S

GROUP BY S.year

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