RELATIONAL DATABASE FUNDAMENTALS
There are three models for organizing information in a database
There are three models for organizing information in a database
1.
1. hierarchical models
2.
2. network models
3.
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.
1. Database:
maintains information about various types of objects (inventory), events
(transactions), people (employees), and places (warehouses)
1.
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.
1.
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
1.
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.
1.
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.
2.
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:
i.Increased flexibility
ii.Increased scalability and performance
iii.Reduced information redundancy
iv.Increased information integrity (quality)
v.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
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