Is it possible to update view in Oracle

Answer: A VIEW in Oracle is created by joining one or more tables. When you update record(s) in a VIEW, it updates the records in the underlying tables that make up the View. So, yes, you can update the data in an Oracle VIEW providing you have the proper privileges to the underlying Oracle tables.

How do I modify a view in Oracle?

To redefine a view, you must use CREATE VIEW with the OR REPLACE keywords. When you issue an ALTER VIEW statement, Oracle Database recompiles the view regardless of whether it is valid or invalid. The database also invalidates any local objects that depend on the view.

Can we update view in SQL?

yes we can insert,update and delete view in sql server. View is the virtual table, yes we can.

Can a database view be updated?

Yes, they are updatable but not always. Views can be updated under followings: If the view consists of the primary key of the table based on which the view has been created. If the view is defined based on one and only one table.

Can we update complex view in Oracle?

YES, you can Update and Insert into view and that edit will be reflected on the original table….

How view is created and dropped?

Creating Views Database views are created using the CREATE VIEW statement. Views can be created from a single table, multiple tables or another view. To create a view, a user must have the appropriate system privilege according to the specific implementation. CREATE VIEW view_name AS SELECT column1, column2…..

Can we create view without table in Oracle?

A view can be created even if the defining query of the view cannot be executed. … For example, if a view refers to a non-existent table or an invalid column of an existing table or if the owner of the view does not have the required privileges, then the view can still be created and entered into the data dictionary.

How do I edit a SQL view?

1. In Object Explorer, click the plus sign next to the database where your view is located and then click the plus sign next to the Views folder.
2. Right-click on the view you wish to modify and select Design.

Are views more efficient than queries?

Views make queries faster to write, but they don’t improve the underlying query performance. … In short, if an indexed view can satisfy a query, then under certain circumstances, this can drastically reduce the amount of work that SQL Server needs to do to return the required data, and so improve query performance.

What happens when we update views?

Yes, when you update a view it affects original table, because SELECT opens an implicit cursor which points to the records from the base table. When ever you update the records it updates the original data since they are pointers to the original.

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Can we perform DML on view?

DML operations could be performed through a simple view. DML operations could not always be performed through a complex view. INSERT, DELETE and UPDATE are directly possible on a simple view. We cannot apply INSERT, DELETE and UPDATE on complex view directly.

What is difference between view and table?

The main difference between view and table is that view is a virtual table based on the result set of an SQL statement, while a table is a database object that consists of rows and columns that store data of a database. … In other words, there should be one or multiple tables to create views.

What is Materialised views in Oracle?

A materialized view is a database object that contains the results of a query. … You can select data from a materialized view as you would from a table or view. In replication environments, the materialized views commonly created are primary key, rowid, object, and subquery materialized views.

How many types of views are there?

The two main types of views (or “projections”) used in drawings are: pictorial. orthographic.

What is an Editionable view?

EDITIONABLE is a keyword relating to Edition-based Redefinition. This is a mechanism Oracle provides which allows us to support multiple versions of the same object in our database. This can be very useful for wrangling complex deployments in live environments.

Which conditions will create read-only views?

A view is read-only if it is not deletable, updatable, or insertable. A view can be read-only if it is a view that does not comply with at least one of the rules for deletable views.

What are the advantages of view?

• Views can represent a subset of the data contained in a table. …
• Views can join and simplify multiple tables into a single virtual table.
• Views can act as aggregated tables, where the database engine aggregates data (sum, average, etc.) …
• Views can hide the complexity of data.

Does create or replace view drop Grants?

Basically, a self-descriptive command is: grant select on view_1 to schema_1 . However, it is quite possible that SQL developer invokes drop view first instead of create or replace . In this case, your privileges are automatically removed.

Does index take space in disk?

Does index take space in the disk? Explanation: Indexes take memory slots which are located on the disk.

What happens to view when table is dropped in Oracle?

Dropping a table removes the table definition from the data dictionary. All rows of the table are no longer accessible. All indexes and triggers associated with a table are dropped. All views and PL/SQL program units dependent on a dropped table remain, yet become invalid (not usable).

What is the need of view in DBMS?

A view is used for security purpose in the database and act as an intermediate between real tables schema & programmability.It also restricts the user from viewing certain columns and row as well, View always represents custom output which is mentioned in the query & returns that data everytime which defined in the …

Can we do indexing on view?

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.

Are views bad for performance?

The danger with using views is filtering a query against a view, expecting to read a very small portion of a very large table. … Views are typically useful for speeding up the development process but in the long run can completely kill database performance.

Is view better than table?

A table contains data, a view is just a SELECT statement which has been saved in the database (more or less, depending on your database). The advantage of a view is that it can join data from several tables thus creating a new view of it.

When I update a table in SQL does my view get updated?

Yes, they are updated, every time you use them. Views are not automatically cached. When you SELECT from a view, the database has to run the query stored in the view to get the result set to use in your statement The data you ‘see’ in a view, is not actually stored anywhere, and is generated from the tables on the fly.

How do I edit 1000 rows in SQL?

1. If you would like to change the default value then go to SSMS > Tools > Options:
2. In the Options dialog box, highlight SQL Server Object Explorer and change the default values to any number as per your requirements.

What is the difference between view and stored procedure?

View is simple showcasing data stored in the database tables whereas a stored procedure is a group of statements that can be executed. A view is faster as it displays data from the tables referenced whereas a store procedure executes sql statements.

Can a trigger be created on a view?

Triggers may be created on views, as well as ordinary tables, by specifying INSTEAD OF in the CREATE TRIGGER statement. If one or more ON INSERT, ON DELETE or ON UPDATE triggers are defined on a view, then it is not an error to execute an INSERT, DELETE or UPDATE statement on the view, respectively.

Which operation is not allowed in JOIN?

To be modifiable, a join view must not contain any of the following: Hierarchical query clauses, such as START WITH or CONNECT BY. GROUP BY or HAVING clauses. Set operations, such as UNION, UNION ALL, INTERSECT, MINUS.

Is it possible to create a view from another view?

You can certainly have a view that’s built on top of another view: create table my_table (id number, name varchar2(20), address varchar2(30)); table MY_TABLE created.

Can you update complex view if no why?

YES–> If it is in the case of simple view (which consists only one base table). NO—->If it is in the case of complex view( which consists multiple base tables, and joins).