Page 67 - DLIS408_INFORMATION_TECHNOLOGY-APPLICATIONSL SCIENCES

Information Technology and Application

Notes application’s data structures may be changed or added, new related application programs may be
written to add to the application’s functionality, etc.

Database Storage
Database storage is the container of the physical materialization of a database. It comprises the
Internal (physical) level in the Database architecture. It also contains all the information needed
(e.g., metadata, “data about the data”, and internal data structures) to reconstruct the Conceptual
level and External level from the Internal level when needed. Though typically accessed by a
DBMS through the underlying Operating system (and often utilizing the operating systems’ File
systems as intermediates for storage layout), storage properties and configuration setting are
extremely important for the efficient operation of the DBMS, and thus are closely maintained by
database administrators. A DBMS, while in operation, always has its database residing in several
types of storage (e.g., Computer memory and external Computer data storage, as dictated by
contemporary computer technology. The database data and the additional needed information are
coded into bits, possibly in very large amounts. Data typically reside in the storage in structures
that look completely different from the way the data look in the conceptual and external levels,
but in ways that attempt to optimize (the best possible) these levels’ reconstruction when needed
by users and programs, as well as for computing additional types of needed information from the
data (e.g., when querying the database).
In principle the database storage (as computer data storage in general) can be viewed as a linear
address space (a tree-like is a more accurate description), where every bit of data has its unique
address in this address space. Practically only a very small percentage of addresses is kept as initial
reference points (which also requires storage), and most of the database data is accessed by
indirection using displacement calculations (distance in bits from the reference points) and data
structures (see below) which define access paths (using pointers) to all needed data in effective
manner, optimized for the needed data access operations.

Database Security
Database security denotes the system, processes, and procedures that protect a database from
unauthorized activity.
DBMSs usually enforce security through access control, auditing, and encryption:
Access control manages who can connect to the database via authentication and what they
can do via authorization.
Auditing records information about database activity: who, what, when, and possibly
where.
Encryption protects data at the lowest possible level by storing and possibly transmitting
data in an unreadable form. The DBMS encrypts data when it is added to the database and
decrypts it when returning query results. This process can occur on the client side of a
network connection to prevent unauthorized access at the point of use.

Benefits of Database Management
Database management systems are programmes that are written to store, update, and retrieve
information from a database.

Notes There are many databases available in the market. The most popular are the Oracle
and SQL Server.

The Oracle database is from the Oracle Corporation and the SQL Server is from the Microsoft
Corporation. There are freely available database like MySQL. These are open source databases.

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