SQL Statements › CREATE VIEW › Processing

Processing

A view is read-only and cannot be updated if its definition includes any of the following phrases:

• A FROM clause naming more than one table or view (a join)
• The keyword DISTINCT
• A GROUP BY clause

Keywords and phrases which cannot be used in the definition of a view are:

• FOR UPDATE OF
• ORDER BY
• UNION

Note: A view whose definition involves either a GROUP BY clause or a column function cannot be named in any FROM clause that contains another table or view, that is to say, the view cannot be joined. This is not a restriction on the content of the CREATE VIEW statement itself, but on queries that reference the view. An error message is issued if you violate this rule. Also, a view whose definition contains a SELECT DISTINCT may only be joined if the join itself has a SELECT DISTINCT. Again, this is a restriction on queries that reference the view, not a restriction on the view itself.