When you delete rows from an updateable view, Oracle Database deletes rows from the base table. You cannot delete rows from a read-only materialized view. When you delete rows from a writable materialized view, the database deletes the rows from the underlying container table.
Can we delete records from the view?
You can insert, update, and delete rows in a view, subject to the following restrictions: If the view contains links between multiple tables, you can insert and update only one table in the view, and you cannot delete rows. You cannot directly edit data in views based on union queries. 13
How to delete a row from a view in SQL?
If you want a row to disappear from a view, you must either delete the data from the actual tables behind the view, or modify the view by writing SQL so that a specific row does not appear in the view. 18
How do I change 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 whether it is valid or not.
How do I delete a record in Oracle?
First enter the name of the table whose data you want to delete. Second, use the condition in the WHERE clause to specify which row to delete. If you omit the WHERE clause, the Oracle DELETE statement deletes all rows from the table.
What happens if you use the delete command without the where clause?
The delete query in SQL should always be executed with the WHERE clause to avoid unwanted data loss. The delete statement without a WHERE clause deletes all records from the table and without a proper recovery mechanism your data could be lost forever.
Are calls faster than queries?
Views speed up query writing, but do not improve the performance of the underlying queries. …once we create an indexed view, whenever data in the underlying tables changes, SQL Server not only has to maintain the index entries for those tables, but also the index entries that are being viewed. 12
What is the syntax for deleting the view?
If you want to drop a SQL view, it is done with the SQL command DROP, you must use the following syntax: SQL syntax DROP VIEW: DROP VIEW name_view.
Can we insert and delete rows in a mcq view?
Explanation: Yes, we insert and delete rows in a view.
How do you change the view?
If you remember the CREATE VIEW SQL syntax, a view can be altered by simply using the ALTER VIEW keyword instead, and then changing the structure of the SELECT statement. Therefore, let’s alter the view previously created with the SQL CREATE VIEW statement using the ALTER VIEW statement.
Can we change the view in SQL?
If the view contains links between multiple tables, you can only insert and update a table in the view, and you cannot delete rows. You cannot directly edit data in views based on union queries. You cannot change data in views that use GROUP BY or DISTINCT statements.
What is the difference between truncation and deletion in Oracle?
Data can be removed from the table with the two commands Delete and Truncate. Delete is a DML command while truncate is a DDL command. Truncate can be used to remove all data from the table without preserving table integrity. On the other hand, the delete statement can be used to delete the specific data.
Do we need to commit after deleting in Oracle?
Oracle Database issues an implicit COMMIT before and after each Data Definition Language (DDL) statement. Oracle recommends that you explicitly end each transaction in your application programs with a COMMIT or ROLLBACK statement, including the last transaction before you disconnect from the Oracle database.