Relational Database Fundamentals
A database maintains information about various types of objects (inventory), events (transactions), people (employees), and places (warehouses).
In a hierarchical database model, 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.
The network database model is a flexible way of representing objects and their relationships.
The relational database model is a type of database that stored 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
§The rows in each table contain the entities
§In Figure 7.1 CUSTOMER includes Dave’s Sub Shop and Pizza Palace entities
Attributes (fields, columns) – characteristics or properties of an entity class
§The columns in each table contain the attributes
§In Figure 7.1 attributes for CUSTOMER include Customer ID, Customer Name, Contact Name
KEYS AND RELATIONSHIPS
A primary key is a field (or group of fields) that uniquely identifies a given entity in a
table.
A 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
From a business perspective, database information offers many advantages,
including:
·Increased flexibility.
The physical view of information deals with the physical storage of information on
a storage device such as a hard disk.
The logical view of information focuses on how users logically access information
to meet their particular business needs.
·Increased scalability and performance.
Scalability refers to how well a system can adapt to increased demands.
Performance measures how quickly a system performs a certain process or
transaction.
·Reduced information redundancy.
Redundancy is the duplication of information, or storing the same information in
multiple places.
·Increased information integrity (quality).
Information integrity is a measure of the quality of information.
Within a database environment, integrity constraints are rules that help ensure the
quality of information.
There are two types of integrity constraints:
Relational integrity constraints are rules that enforce basic and fundamental
information-based constraints.
Business-critical integrity constraints enforce business rules vital to an
organization’s success and often require more insight and knowledge than relational
integrity constraints.
·Increased information security.
Database Management Systems
A database management system (DBMS) is software through which users and
application programs interact with a database.
DATA-DRIVEN WEBSITES
A data-driven website is an interactive website kept constantly updated and relevant to the needs of its customers through the use of a database.
DATA-DRIVEN WEBSITE BUSINESS ADVANTAGES
When building a website, ask two primary questions to determine if the website needs a database:
1.How often will the content change?
2.Who will be making the content changes?
Integrating Information among Multiple Databases
An integration allows separate systems to communicate directly with each other.
Without integrations, an organization will spend considerable time entering the same information in multiple systems and suffer from the low quality and inconsistency typically embedded in redundant information.
A forward integration takes information entered into a given system an sends it automatically to all downstream systems and processes.
A backward integration takes information entered into a given system and sends it automatically to all upstream systems and processes.
