17-08-2012, 01:05 PM
Database Management System MB-205
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Database Management System
(DBMS)
Database Management System or DBMS is
nothing more than a computer base record
keeping system. It is a collection of
interrelated data store together
unnecessary redundancy.
DBMS contains information about a particular enterprise
Collection of interrelated data
Set of programs to access the data
An environment that is both convenient and efficient to use
Database Applications:
Banking: all transactions
Airlines: reservations, schedules
Universities: registration, grades
Sales: customers, products, purchases
Online retailers: order tracking, customized recommendations
Manufacturing: production, inventory, orders, supply chain
Human resources: employee records, salaries, tax deductions
Databases touch all aspects of our lives
Instances and Schemas
Similar to types and variables in programming languages
Schema – the logical database structure of the database
Example: The database consists of information about a set of customers and
accounts and the relationship between them)
Physical schema: database design at the physical level
Logical schema: database design at the logical level
Instance – the actual content of the database at a particular point in
time
Physical Data Independence – the ability to modify the physical
schema without changing the logical schema
Applications depend on the logical schema
In general, the interfaces between the various levels and components should be
well defined so that changes in some parts do not seriously influence others.
Database Administrator
Coordinates all the activities of the database system
has a good understanding of the enterprise’s information
resources and needs.
Database administrator's duties include:
Storage structure and access method definition
Schema and physical organization modification
Granting users authority to access the database
Backing up data
Monitoring performance and responding to changes
Attributes
In general, an attribute is a property or characteristic.
Color, for example, is an attribute of your hair. . In a
database management system (DBMS), an attribute
may describe a component of the database, such as a
table or a field, or may be used itself as another term
for a field.
Example: In DBMS, a Table contains one or more
columns. These column(s) are the Attribute in DBMS.
For Example, say you have a table named "Employee"
which have the following columns:ID, Name, Address.
Then "ID", "Name" and "Address" are the attributes of
Employee table.