SQL View | Types ,Benefits and Example
Sql view represents subsets of data from one or more tables.
A view can contain all rows of a table or select rows from a table.
- A view is a virtual table based on the result-set of an SQL statement
- With the help of view, We can get virtual view of selected data without affecting data of real table
- It contains rows and columns just like a real table
- It store data dynamically.
- It also prevents to access real table.
Create A VIEW
CREATE VIEW view_name AS SELECT column_name(s) FROM table_name where [condition]
Modify a View
Alter VIEW view_name AS SELECT column_name(s) FROM table_name where [condition]
Types of SQL View:
1) Simple views
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- Derives data from only one table
- Can perform DML operations
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2) Complex views
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- Derives data from one or more tables.
- Cannot perform DML operations as data is derived from one or more tables.
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Why use views ?
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- To Restrict data access.
- To make complex queries easy.
- Views can be used to hide and reuse complex queries.
- This allows the DBA to give users only the data they need, while protecting other data in the same table.
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Reference – https://docs.oracle.com/cd/B28359_01/server.111/b28310/views001.htm#ADMIN11774
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