View

Definition

A view is a virtual table in a database that is based on the result of a SELECT query. It allows users to simplify complex queries and provide a way to present data in a specific format, while also maintaining data security by restricting access to specific rows or columns of underlying tables. Views act as a layer of abstraction, making it easier to manage data and manipulate how it's displayed without altering the actual data in the database.

5 Must Know Facts For Your Next Test

1. Views do not store data themselves; instead, they store the SQL query that defines how to retrieve the data from one or more underlying tables.
2. Because views can include SELECT statements with joins, filters, and aggregations, they can provide customized perspectives on the data without duplicating it.
3. Users can be granted permissions on views without providing access to the underlying tables, enhancing security and control over sensitive data.
4. Views can be used to simplify the complexity of user queries, making it easier for users who may not have extensive SQL knowledge to interact with the data.
5. When underlying tables are updated, any changes are automatically reflected in the view, ensuring that users always see the most current data without needing to refresh manually.

Review Questions

• How do views enhance data management and user interaction with databases?
  • Views enhance data management by allowing users to interact with complex data sets through simplified representations. They provide a way to encapsulate complex SELECT statements, so users can retrieve needed information without understanding the underlying structure. Additionally, views improve security by restricting access to sensitive information while still allowing users to perform queries on the relevant data.
• Discuss the differences between views and materialized views in terms of data storage and performance.
  • The main difference between views and materialized views lies in how they handle data storage and performance. A standard view does not store any data; it dynamically retrieves information each time it is accessed based on its underlying SQL query. In contrast, a materialized view stores the result of the query physically on disk. This precomputation allows materialized views to improve performance for complex queries since they can return results faster than standard views that need to recompute results each time.
• Evaluate how views can impact database security while facilitating user access to necessary information.
  • Views play a significant role in enhancing database security by allowing administrators to control user access to sensitive information. By granting users permission to access specific views rather than direct access to underlying tables, administrators can restrict visibility of certain columns or rows that contain confidential data. This means users can still perform necessary queries and obtain insights from the database without compromising overall security, thereby balancing usability with privacy concerns.

Related terms

table:

A table is a collection of related data entries consisting of rows and columns that stores data in a structured format within a database.

SELECT query: A SELECT query is a command used to retrieve data from one or more tables in a database, allowing for filtering, sorting, and aggregation of results.

materialized view: A materialized view is a physical copy of the data retrieved by a view, stored on disk, which can improve performance for complex queries by precomputing and storing the results.