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How can we restrict an updatable view?
SAP ASE prohibits delete statements on multitable views, but allows update and insert statements that would not be allowed in other systems. You can insert or update a multitable view if: The view has no with check option clause. All columns being inserted or updated belong to the same base table.
What is not possible in an updatable view?
If a view is not updatable, statements such UPDATE , DELETE , and INSERT are illegal and are rejected. (Even if a view is updatable, it might not be possible to insert into it, as described elsewhere in this section.)
Which Cannot be done on a view?
What cannot be done on a view? Explanation: In MySQL, ‘Views’ act as virtual tables. It is not possible to create indexes on a view. However, they can be used for the views that are processed using the merge algorithm.
When is a view considered to be updatable?
A view is updatable if the statement against the view can be translated into the corresponding statement against the underlying table. Let’s consider the following database tables: In database diagram, a car belongs to one brand while a brand has one or many cars.
When do MySQL triggers activate in updatable views?
Important: MySQL triggers activate only for changes made to tables by SQL statements. They do not activate for changes in views, nor by changes to tables made by APIs that do not transmit SQL statements to the MySQL server. Be on the lookout if you use and depend on triggers, since it’s not the case for updatable views!
Can a view be manipulated by a table?
However, you cannot always manipulate data via views. A view is updatable if the statement against the view can be translated into the corresponding statement against the underlying table. Let’s consider the following database tables:
Which is the updatable column in the All cars view?
Set operators e.g., UNION, UNION ALL, INTERSECT, and MINUS. To find which column can be updated, inserted, or deleted, you use the user_updatable_columns view. The following example shows which column of the all_cars view is updatable, insertable, and deletable: