Assalamualaikum. Okay, now I have to
proceed to chapter 7.
Let me tell you with details in this
chapter.
We are going to learn how and where all the information is stored. All the organizational information is stored in a database. But the information is stored based on the concept of database that has been collected. Mostly the information is a collection of records, or pieces of information. Typically, a given database has a structural description of the type of facts held in that database. This description called as a schema. The schema describes the objects that are represented in the database and the relationship among them.
RELATIONAL DATABASE
FUNDAMENTALS
There are three models for organizing information in a database
There are three models for organizing information in a database
- 1. hierarchical models
- 2. network models
- 3. relational database models
From the transactional and analytical
information, everything will be stored in database but the information will be
store into its type itself. For example, if the information that been store is
about marketing, so it will be group in marketing information in database.
Definition:
- 1. Database: maintains information about various types of objects (inventory), events (transactions), people (employees), and places (warehouses)
- 2. Hierarchical models: information is organized into a tree-like structure that allows repeating information using parent/child relationships in such a way that it cannot have too many relationships in such a way that it cannot have too many relationships. However, it cannot be used to relate to structures that exist in the real world.
- 3. Network database model: flexible way of representing objects and their relationships. It is where it likes a tree of record with each record having one parent record and many children. Network model allows each record to have multiple parent and child record, forming a lattice structure
- 4. Relational database model: types of database that more prevalent because stores information in the form of logically related two-dimensional tables. Good database can handle changes quickly and easily
ENTITIES AND ATTRIBUTES
ENTITIES: in the relational database
model is a person, place, thing, transaction, or event about which information
is stored. A table in the relational database model is a collection of
similar entities.
ATTRIBUTES: is called fields or columns, are characteristics
or properties of an entity class. The
columns in each table contain the attributes
KEYS
AND RELATIONSHIPS
To manage and organize various entity
classes within the relational database model, developers must identify primary
keys and foreign keys and use them to create logical relationships.
- Primary keys: a field (or group of fields) that uniquely identifies a given entity in a table. It is important because they provide a way of distinguishing each entity in a table.
- Foreign key: in the relational database model is a primary key of one table that appears as an attribute in another table and acts to provide a logical relationship between the two tables.
RELATIONAL DATABASE ADVANTAGES:
- Increased flexibility
- Increased scalability
and performance
- Reduced information
redundancy
- Increased information
integrity (quality)
- Increased information
security
i.
INCREASE FLEXIBILITY :
·
A well-designed database
should handle changes quickly and easily, provide users with different views
and have only one physical view
·
The distinction between
logical and physical view is very important in understanding flexible database
user views.
a.
Physical view: it deal with the physical storage of
information on a storage device such as a hard disk.
b.
Logical view: focuses on how users logically access
information to meet their particular business needs.
ii.
INCREASED SCALABILITY AND PERFORMANCE
· A database must scale to
meet increased demand, while maintaining acceptable performance levels
·
Scalability: how well a system can adapt to increased demands
·
Performance: measure how quickly a system can adapt to increased demands
iii.
REDUCED INFORMATION REDUNDANCY
· Redundancy: the duplication of information or storing
the same information in multiple places.
·
Inconsistency is one of the primary problems with
redundant information.
· Goal of
database is to eliminate redundancy by put the information in one place in the
database. Thus it can save space, perform the information easier and improve
the quality.
iv.
INCREASED INFORMATION INTEGRITY (QUALITY)
·
Information integrity: measures the
quality of information
· Integrity constraint:
rules that help ensure the quality of information and built into a
database design. It can be divided into two types:-
a. Relational integrity constraint: rules that enforce basic and
fundamental information based constraint.
b.
Business-critical
integrity constraint: enforce business rules vital to an organization’s success and
often require more insight and knowledge than relational integrity constraint.
v.
INCREASED INFORMATION SECURITY
·
Information is an organizational asset and must
be protected
·
Databases offer several
security features including:
a) Password: provides authentication of the user who is gaining and access to
the system
b) Access level: determines who has access to the different types of information
c) Access control:
determines types of user access, such as read-only
access
DATABASE MANAGEMENT
SYSTEMS
A database management system (DBMS) is
software through which users and application programs interact with a database.
It is where, the users send requests to the DBMS and the DBMS performs the
actual manipulation of the information in the database. It can interact with
two ways; directly or indirectly. DBMS is software for the users to access for communicate
to get the information in database.
INTEGRATING
INFORMATION AMONG MULTIPLE DATABASE
Ø
Integration: allows separate systems to
communicate directly with each other.
Ø
Method of integration:
i.
Forward integration: takes information entered into a given system and sends it
automatically to all downstream systems and processes
ii.
Backward integration: takes information entered into a given system and sends it
automatically to all upstream systems and processes
XIExie ni....
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