Databases

Question 1

In general, an SQL view is said to be updatable (i.e., inserts, updates, or deletes can be applied on the view) if the following conditions are all satisfied by the query defining the view:

Answer 1

• The from clause has only one database relation.
• The select clause contains only attribute names of the relation and does not have any expressions, aggregates, or distinct specification. • Any attribute not listed in the select clause can be set to null; that is, it does not have a not null constraint and is not part of a primary key.
• The query does not have a group by or having clause.