Oracle views

An updatable view allows DML statements.

If the view's select must not have one of the following SQL operators or constructs to be updatable:

• Set operators (union, minus etc.)
• distinct
• aggregate functions (such as count etc.) / group by clause
• Analytic functions
• order by
• Model clause
• start with, connect by clauses
• Subqueries in the select list

In addition, some types of joins also make a view unupdatable.

Triggers on views

Inline views

dba_views, dba_catalog

An SQL statement that references views can be transformed into a statement with the identical meaning, but without referencing any views (or synonyms for that matter) with dbms_utility.expand_sql_text.

A view cannot select from itself, trying to create such a view results in ORA-01731: circular view definition encountered.

Database objects

ORA-04063: view … has errors