The ANSI/SPARC Architecture of a Database Environment 1 Lecture
2 Slide 2 The ANSI/SPARC Architecture of a Database Environment 2
Schema and instance database schema the description of the database
is called the database schema or intension; specified at the
creation of the database not expected to change very often database
instance the raw data that populates a database at a particular
moment in time is called a database instance of the extension of
the database Slide 3 The ANSI/SPARC Architecture of a Database
Environment 3 Schema and instance - example Slide 4 The ANSI/SPARC
Architecture of a Database Environment 4 Levels of access to data
Slide 5 The ANSI/SPARC Architecture of a Database Environment 5 The
three ANSI/SPARC levels of abstraction Slide 6 The ANSI/SPARC
Architecture of a Database Environment 6 Schemas and mappings
schemas external conceptual internal mappings external / conceptual
conceptual / internal data catalogue/dictionary schemas mappings
Slide 7 The ANSI/SPARC Architecture of a Database Environment 7
External / conceptual example Slide 8 The ANSI/SPARC Architecture
of a Database Environment 8 Conceptual / internal - example Slide 9
The ANSI/SPARC Architecture of a Database Environment 9 Program -
data independence physical the immunity of application programs to
changes at the internal level logical the immunity of application
programs to changes at the conceptual level Slide 10 The ANSI/SPARC
Architecture of a Database Environment 10 The components of a
database environment Slide 11 The ANSI/SPARC Architecture of a
Database Environment 11 Data types primary derived characteristics
integrated shared extensive data = raw data + data dictionary Slide
12 The ANSI/SPARC Architecture of a Database Environment 12
Hardware storage space permanent / secondary temporary / primary
computational power Slide 13 The ANSI/SPARC Architecture of a
Database Environment 13 Software Slide 14 The ANSI/SPARC
Architecture of a Database Environment 14 Application programs user
developed in a third generation language provide an embedded data
sub-language provided by developers fourth generation language
examples: query processors, statistical packages, reports/forms
generators Slide 15 The ANSI/SPARC Architecture of a Database
Environment 15 Database management system provides support for data
manipulation / definition data sub-languages (computationally
incomplete) data integrity security control recovery services
concurrency facilities data communication accessing the data
dictionary why needed? applications automatic access to the DB
Slide 16 The ANSI/SPARC Architecture of a Database Environment 16
People data administrator relevance and meaning of data; standards;
policy database administrator design, implementation and
maintenance of the DB application programmers end user Slide 17 The
ANSI/SPARC Architecture of a Database Environment 17 Summary the
three level ANSI/SPARC architecture of a database environment the
components of a database environment Slide 18 The ANSI/SPARC
Architecture of a Database Environment 18 Activity A2 Which role
within a database environment would you prefer to be in, if you
were able to choose? Why? Which activities would you be interested
in performing? How would you like to co- operate with the people
performing the other roles?
