Page 63 - DLIS408_INFORMATION_TECHNOLOGY-APPLICATIONSL SCIENCES

Information Technology and Application

Notes Manipulating the Data: Data Manipulation Languages and Query
Languages

The database data models needs support by sufficiently rich Data manipulation languages to
allow DB manipulation and information retrieval from it as needed by the database’s application.
These languages are typically data model specific.

Protecting the Data: Database Security

The DB needs build-in security means to protect its content (and users) from dangers of unauthorized
users (humans or programmes). Also types of unintentional breach are included.

Describing Processes that use the Data: Workflow and Business Process
Modeling

Manipulating database data often involves processes of several interdependent steps, at different
times (e.g., when different people’s interactions are involved; e.g., generating an insurance policy).
Data manipulation languages are typically intended to describe what is needed in a single such
step. Dealing with multiple steps typically requires writing quite complex programs. This area
has evolved in the frameworks of workflow and business processes with supporting languages
and software packages. Traditionally these frameworks have been out of the scope of common
DBMSs, but utilization of them has become common-place, and often they are provided as add-
on’s to DBMSs.

Operational Requirements

Operational requirements are needed to be met by a database in order to effectively support an
application. Though it may be expected that operational requirements are automatically met by a
DBMS, in fact it is not so for most of them: To be met substantial work of design and tuning is
needed by database administrators. It is typically done through special database user interfaces
and tools, and thus may be viewed as secondary functional requirements (but not less important
than the primary).

Availability

A DB should maintain needed levels of availability, i.e., the DB needs to be available in a way that
a user’s action does not need to wait beyond a certain time range before starting executing upon
the DB. Availability also relates to failure and recovery from it (see Recovery from failure and
disaster below): Upon failure and during recovery normal availability changes and special
measures are needed to satisfy availability requirements.

Performance
Users’ actions upon the DB should be executed within needed time ranges.

Isolation Between Users

When multiple users access the database concurrently the actions of a user should be uninterrupted
and unaffected by actions of other users. These concurrent actions should maintain the DB’s
consistency (i.e., keep the DB from corruption).

Recovery from Failure and Disaster
All software systems, including DBMSs, are prone to failures for many reasons (both software and
hardware related). Failures typically corrupt the DB, typically to the extent that it is impossible to

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