13
View of Data
• Data Abstraction
– Physical level
• The lowest level of abstraction describes how the data
are actually stored. The physical level describes
complex low-level data structures in detail.
– Logical level
• The next-higher level of abstraction describes what
data are stored in the database, and what relationships
exist among those data. The logical level thus
describes the entire database in terms of a small
number of relatively simple structures.
– View level
• The highest level of abstraction describes only part of
the entire database.