March 01, 2004
The SQLite Database Engine
Listing 7: Views with triggers.
CREATE VIEW above_average AS SELECT projectname_full, rating
FROM project
WHERE rating > (SELECT AVG(rating) FROM project)
ORDER BY rating DESC;
-- Make the view updatable according to following trigger
CREATE TRIGGER on_update_above_average
INSTEAD OF UPDATE ON above_average
FOR EACH ROW
BEGIN
UPDATE project SET rating=new.rating
WHERE projectname_full=new.projectname_full;
END
-- Now the following update to the view will work:
UPDATE above_average SET rating=10 WHERE projectname_full='Gentoo Linux';
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