Can we delete records from view?

You can insert, update, and delete rows in a view, subject to the following limitations: If the view contains joins between multiple tables, you can only insert and update one table in the view, and you can’t delete rows. You can’t directly modify data in views based on union queries.

How do I delete data from view?

DELETE Rule

Rows from a join view can be deleted as long as there is exactly one key-preserved table in the join. If the view is defined with the WITH CHECK OPTION clause and the key preserved table is repeated, then the rows cannot be deleted from the view.

Can we delete record from view in Oracle?

Specify the name of a table, view, materialized view, or the column or columns resulting from a subquery, from which the rows are to be deleted. When you delete rows from an updatable view, Oracle Database deletes rows from the base table. You cannot delete rows from a read-only materialized view.

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What command is used to delete a view?

If you want to delete a SQL view, It is done by SQL DROP command you should use the following syntax: SQL DROP VIEW syntax: DROP VIEW view_name.

What 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.

Which view does not always allow DML operations through the 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.

Is stored only in the master database?

Explanation: Server-scoped Dynamic Management View is stored only in the Master database.

How do you delete duplicate records in Oracle?

Delete duplicate rows by identifying their column.

After «SQL'» enter «delete from names a where rowid > (select min(rowid) from names b where b.name=a.name and b. age=a. age);» to delete the duplicate records.

Are views updatable?

All views are not updatable. So, UPDATE command is not applicable to all views. An updatable view is one which allows performing a UPDATE command on itself without affecting any other table.

Can we insert and delete rows into a view?

If the view contains joins between multiple tables, you can only insert and update one table in the view, and you can’t delete rows. You can’t directly modify data in views based on union queries.

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What Is syntax for delete the view Mcq?

What is syntax for delete the view? Explanation: The syntax is very simple and is given below : DROP VIEW view_name; 7. All NOT NULL columns from the base table must be included in the view in order for the INSERT query to function.

Which SQL statement would you use to remove a view?

The correct answer is option D (DROP VIEW emp_dept_vu). We can use a DROP statement to remove a view from the database.

Why do we create view in SQL?

Views are virtual tables that can be a great way to optimize your database experience. Not only are views good for defining a table without using extra storage, but they also accelerate data analysis and can provide your data extra security.

What are the four different types of view?

Explain the different between all four types of views available.

  • Database View ( SE11 ) …
  • Help View ( SE54 ) …
  • Projection View. …
  • Maintenance View ( SE54 )

Can we create view from view?

Creating Views

Database views are created using the CREATE VIEW statement. … CREATE VIEW view_name AS SELECT column1, column2….. FROM table_name WHERE [condition]; You can include multiple tables in your SELECT statement in a similar way as you use them in a normal SQL SELECT query.

Can we perform DML operations on views?

Yes, View Is Virtual table. … In simple view We create view on single base table That’s why we can perform all DML operations.it also called as Updatable view. But In case of Complex view We create view on multiple base tables that’s why we cannot perform DML operations It is ReadOnly View (Only Select Operation).