Views

• A ‘virtual table’
• A relation defined in terms of the contents of other tables and views
• CREATE VIEW <name> AS <query>
• A table whose values are actually stored in the database is called a ‘base table’
• Triggers on views
  • Generally, it is impossible to modify a view because it doesn’t exist
  • But an INSTEAD OF triggers lets us interpret view modifications as modifications over base tables
• Materialized Views
  • Precompute result of a view
  • Periodically reconstruction of the materialized views which are otherwise out of date