What are updatable views in Oracle?

What are updatable views in Oracle?

An updatable view is one you can use to insert, update, or delete base table rows. You can create a view to be inherently updatable, or you can create an INSTEAD OF trigger on any view to make it updatable.

Which views are updatable?

An updatable view is a special case of a deletable view. A deletable view becomes an updatable view when at least one of its columns is updatable. A column of a view is updatable when all of the following rules are true: The view is deletable.

Which views are updatable in SQL?

A deletable view becomes an updatable view when at least one of its columns is updatable. A column of a view is updatable when all of the following rules are true: The view is deletable. The column resolves to a column of a table (not using a dereference operation) and the READ ONLY option is not specified.

Under what circumstances is a view said to be updatable in Oracle?

A view behaves like a table because you can query data from it. 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.

What are updatable views in SQL Server?

Updatable Views

• Any modifications, including UPDATE, INSERT, and DELETE statements, must reference columns from only one base table.
• The columns being modified in the view must directly reference the underlying data in the table columns.

Can you create an index on updatable views?

Indexes can only be created on views which have the same owner as the referenced table or tables. This is also called an intact ownership-chain between the view and the table(s). Typically, when table and view reside within the same schema, the same schema-owner applies to all objects within the schema.

Which statement is not valid for an updatable view?

If a view is not updatable, statements such UPDATE , DELETE , and INSERT are illegal and are rejected.

How do I make SQL view updatable?

However, to create an updatable view, the SELECT statement that defines the view must not contain any of the following elements:

1. Aggregate functions such as MIN, MAX, SUM, AVG, and COUNT.
2. DISTINCT.
3. GROUP BY clause.
4. HAVING clause.
5. UNION or UNION ALL clause.
6. Left join or outer join.

What is not possible in an updatable view?

Do indexes work on views?

Indexes can only be created on views which have the same owner as the referenced table or tables.

How do I check if a view is updatable?

You can check if a view in a database in updatable by querying the is_updatable column from the views table in the information_schema database.

How do I create an updatable view?

How do I create a table in Oracle?

Follow these steps to create a table in Oracle SQL developer. Open Oracle SQL Developer. Connect to the Database. On the left side, click on the schema name to expand the node. Then select Table node and do the right click on it. Select New Table option from the shortcut menu to create a table.

What is a materialized view in Oracle?

Oracle Materialized Views. A materialized view is a database object that contains the results of a query. The FROM clause of the query can name tables, views, and other materialized views. Collectively these objects are called master tables (a replication term) or detail tables (a data warehousing term).

What are the types of Oracle view?

There r two types of VIEW in ORACLE. Simple View and Complex View. simple view derives data from only one table but complex view derives data from many table. simple view contain no functions or group of data but complex view contain function or group of data.

What is Oracle SQL view?

A view in oracle is nothing but a stored sql scripts. Views itself contain no data. A view is simply any SELECT query that has been given a name and saved in the database. For this reason, a view is sometimes called a named query or a stored query.