RELATIONAL DATABASE FUNDAMENTALS
- Information is everywhere in an
organization
- Information is stored in databases
Ø Database – maintains information about various
types of objects (inventory), events (transactions), people (employees), and
places (warehouses)
- Database models include;
Ø Hierarchical database model – information is
organized into a tree-like structure (using parent/child relationships) in such
a way that it cannot have too many relationships.
Ø Network
database model – a flexible way of representing objects and their relationships
Ø Relational
database model – stores information in the form of logically related
two-dimensional tables
ENTITIES AND ATTRIBUTES
- Entity – a person, place, thing,
transaction, or event about which information is stored
Ø The rows in each table contains the entities
- Attributes (fields, columns) –
characteristics or properties of an entity class
Ø The columns in each table contain the
attributes
KEYS AND RELATIONSHIPS
- Primary keys and foreign keys identity
the various entity classes (tables) in the database
Ø Primary key – a fields (or group of fields)
that uniquely identities a given entity in a table
Ø Foreign key – a primary key of one table that
appears an attribute in another table and acts to provide a logical
relationships among the two tables
Relational Database Advantages
A) Increased flexibility
A well-designed database should;
Handle changes quickly and easily
Provide users with different views
Have only one physical views
Physical view – deals with the physical storage of
information on a storage device
Have multiple logical views
Logical view – focuses on how users logically access
information
B) Increased scalability and performance
A database must scale to meet increased demand, while
maintaining acceptable performance levels
Scalability – refers to how well a system can adapt to
increased demands
Performance – measures how quickly a system performs a
certain process or transaction
C) Reduced information redundancy
Databases reduce 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
D) Increased information integrity (quality)
Information integrity – measures the quality of
information
Integrity constraint – rules that help ensure the quality of
information
Relational integrity constraint-rule that enforces basic and
fundamental information-based constraints
Eg. Users cannot create an order for a nonexistent customer ;
An order cannot be shipped without an address
E) Increased information security
Information is an organization asset and must be
protected
Databases offer several security features including;
Password – provides authentication of the user
Access level – determines who has access to the
different types of information
Access control – determines types of user access, such
as read-only access
Database Management Systems
A database management systems (DBMS) is software through
which users and application programs interact with a database.
Data-Driven Websites
A data-driven website is an interactive website keep
constantly updated and relevant to the needs of its costumer through the use of
a database.
Data-Driven Website Advantages
Development : Allows the website owner to make changes any
time
Content management : A static website requires a programmer
to make updates.
Future expandability : Having a data-driven website enables
the site to grow faster than would be possible with a static site.
Minimizing human error
Cutting production and update costs
More efficient
Improved stability
Integrating Information among Multiple Databases
An integration allows separate systems to communicate
directly with each other.
A forward integration takes information entered into a
given system and sends it automatically to all downstream processes.
A backward integration takes information entered into a
given systems and sends it automatically to all upstream systems and processes
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