2.1.28. Creating views

  • Views are partial projections
  • Virtual relations, or views of live relations
  • Update synchronised
    • CREATE VIEW <virtual_relname>
    • AS <real_relation>
  • Real relation could be a query result
  • Clever bit is the change propagation
  • UPDATEs made to the view dataset are flooded back to relations
    • INSERT and DELETE behaviour needs to be defined
    • Non-trivial as INSERT into view (virtual relation) may leave holes in real relation