Editing Abstraction (computer science) (section)

===Database systems===
{{Further|Database management system}}

Since many users of database systems lack in-depth familiarity with computer data-structures, database developers often hide complexity through the following levels:

[[Image:Data abstraction levels.png|thumb|Data abstraction levels of a database system]]

''Physical level'' – The lowest level of abstraction describes ''how'' a system actually stores data. The physical level describes complex low-level data structures in detail.

''Logical level'' – The next higher level of abstraction describes ''what'' data the database stores, and what relationships exist among those data. The logical level thus describes an entire database in terms of a small number of relatively simple structures. Although implementation of the simple structures at the logical level may involve complex physical level structures, the user of the logical level does not need to be aware of this complexity. This is referred to as [[physical data independence]]. [[Database administrator]]s, who must decide what information to keep in a database, use the logical level of abstraction.

''View level'' – The highest level of abstraction describes only part of the entire database. Even though the logical level uses simpler structures, complexity remains because of the variety of information stored in a large database. Many users of a database system do not need all this information; instead, they need to access only a part of the database. The view level of abstraction exists to simplify their interaction with the system. The system may provide many [[view (database)|view]]s for the same database.