View technology is now almost all relational databases, and its applications are also very wide.
Adoption of view
1. Let the database structure realize logically expandability: When the physical information of the database system (mainly finger table data, table data) has been completed, if the new business requirements are not enough, the view can be used. Techniques are expanded, and functions are completed through powerful SQL in the view.
2, software development and data query processing Easy: Adoption of the view can simplify the internal structure of the database system and its relationship map, because the physical form is established by the data redundancy analysis, especially in data redundancy processing, which will generate Larger differences, using the view, multiple tables can be united through SQL, resulting in data results that are adapted to the actual business, which greatly facilitates software development and data queries, which is relatively simple to use the SQL written by the view.
View analysis by function
1, business view
Business views are more in database applications, often implementing a specific business results feature, complexity, with complexity, this view often only uses a fixed module in the software, so it is created This view should consider whether the generated business data information is useful and complete, and the data that is not needed is not returned. If the data generated from other tables should be considering generated in the view, not the SQL when the software is required, not in the SQL of the software development through the table link produce.
2, basic view
Basic view refers to a view that may be used in software development, which is generally relatively simple, not more than four table links, and should make detailed analysis when handling basic views, make it Reuse reaches the maximum, do not create a basic view because of the current SQL processing. The table in the basic view should not be repeated in the SQL outside, otherwise the phenomenon of Oracle repeat processing may be caused.
View establishment of:
In the view, if a Union operation occurs, the data is not repeated, it should be changed to the Union ALL to increase the speed.
A view that is substantially the same should analyze if it can be combined into a view without affecting performance and data, which helps software modular development and debugging.
Non-software and unopened views can be saved after using the SQL to make a file re-deletion to avoid affecting other people.
