There are so many important things about views.In this post i am sharing few of important things:
1. A view is like a virtual table. It takes the yield of an inquiry and treats it like a table.
2. A view might be dependent upon one or more tables or different views. These tables/views are called base tables.
3. A view consumes no space other than for the meaning of the view in the information in data dictionary.
4. A view holds no information. All the information it shows originates from the base tables.
5. A view can give an extra level of table security by limiting access to a set of columns or segments of a table.
6. A view conceals execution many-sided quality. The client can select from the view with a straightforward SQL, ignorant that the view is built inside in light of a join between different tables.
7. A view gives you a chance to change the information you can access, applying administrators, accumulation capacities, channels and so on the base table.
8. A view disengages requisitions from progressions in meanings of base tables. Assume a view utilizes two segments of a base table, it has no effect to the view if different sections are included, altered or evacuated from the base table.
9. using views energizes the utilization of imparted SQL, which enhances effectiveness of as often as possible conjured SQL.
10. an updatable view permits you to embed, upgrade, and erase pushes by proliferating the progressions to the base table. A view could be updatable furnished its definition does not hold any of the accompanying develops: SET or DISTINCT specialists, a total or scientific capacity, a GROUP BY, ORDER BY, CONNECT BY, or START WITH statement, a subquery (or accumulation articulation) in a SELECT record.
11. the information concordance views All_updatable_columns, Dba_updatable_columns,and User_updatable_columns demonstrate which view sections are updatable.
12. views that are not updatable could be altered utilizing an INSTEAD OF trigger.
13. a view could be made regardless of the possibility that the characterizing inquiry of the view can’t be executed, utilizing the CREATE FORCE VIEW summon. Such a view is known as a view with failures. This choice could be suitable for import/installation instruments to make a view before the underlying articles are available.
14. a view could be reinstated with a CREATE OR REPLACE VIEW proclamation. The REPLACE choice redesigns the present view definition however saves the present security approvals.
15. a view gives you a chance to reorder sections effortlessly with a CREATE OR REPLACE, as opposed to going into an untidy drop segment for the base table with information.
16. to think about the views in your own particular outline, find user_views.
17. the underlying SQL meaning of the view could be perused through select content from user_views for the view.
18. oracle does not implement demands on views. Rather, views are liable to the demands of their base tables.
19. be watchful when you characterize views of views. Don’t do it simply on the grounds that it is not difficult to code – it may not be the optimal inquiry. Check assuming that you might be better off utilizing the base tables straightforwardly.
20. to make a view in your own particular pattern, you must have the CREATE VIEW framework benefit. To make a view in an alternate client’s pattern, you must have the CREATE ANY VIEW system privilige