The syntax for the CREATE VIEW Statement in Oracle/PLSQL is: CREATE VIEW view_name AS SELECT columns FROM tables [WHERE conditions]; view_name . The name of the Oracle VIEW that you wish to create .
How do I create a view in Oracle?
The syntax for the CREATE VIEW Statement in Oracle/PLSQL is: CREATE VIEW view_name AS SELECT columns FROM tables [WHERE conditions]; view_name . The name of the Oracle VIEW that you wish to create .
What is view in Oracle and how will you create it?
Views are virtual tables formed by a query . A view is a dictionary object that you can use until you drop it. Views are not updatable. If a qualified view name is specified, the schema name cannot begin with SYS.
How do I create a view in Oracle SQL Developer?
In the Connections navigator in SQL Developer, navigate to the Views node in the HR schema , by following the instructions in “Displaying Views”. Right-click the Views node and select New View. The Create View dialog box appears, with the SQL Query tab displayed.
How a view is created?
Views in SQL are kind of virtual tables. A view also has rows and columns as they are in a real table in the database. We can create a view by selecting fields from one or more tables present in the database . A View can either have all the rows of a table or specific rows based on certain condition.
What is true view?
Explanation: VIEW is a virtual table , through which a selective portion of the data from one or more tables can be seen. A view do not contain data of their own.
How many types of views are there in Oracle?
There are 2 types of Views in SQL: Simple View and Complex View. Simple views can only contain a single base table. Complex views can be constructed on more than one base table.
What is the difference between view and materialized view?
Views are generally used when data is to be accessed infrequently and data in table get updated on frequent basis. On other hand Materialized Views are used when data is to be accessed frequently and data in table not get updated on frequent basis.
How do you create a materialized view?
Use the CREATE MATERIALIZED VIEW statement to create a materialized view. 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.
Can we create table from view?
SQL Server does not support CREATE TABLE AS SELECT . This will create a new table A with the contents of your view.
Which will create read only views?
A read-only view can be made updatable by means of triggers . A view will be read-only if its SELECT statement has any of the following characteristics: Specifies a row quantifier other than ALL (i.e., DISTINCT, FIRST, SKIP) Contains fields defined by subqueries or other expressions.
Can we alter view in Oracle?
Use the ALTER VIEW statement to explicitly recompile a view that is invalid or to modify view constraints. 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.
What are triggers in Oracle?
A trigger is a named PL/SQL block stored in the Oracle Database and executed automatically when a triggering event takes place. The event can be any of the following: A data manipulation language (DML) statement executed against a table e.g., INSERT , UPDATE , or DELETE .
How do you write a view?
The syntax for the CREATE VIEW statement in SQL is: CREATE VIEW view_name AS SELECT columns FROM tables [WHERE conditions]; view_name. The name of the SQL VIEW that you wish to create.
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.
How do you write a trigger?
create trigger [trigger_name]: Creates or replaces an existing trigger with the trigger_name. [before | after]: This specifies when the trigger will be executed. {insert | update | delete}: This specifies the DML operation. on [table_name]: This specifies the name of the table associated with the trigger.
