Download ITE252 Slide 1 - Nassau Community College

ITE252 Slide 1
Introduction to Database Management Systems
By: Prof. Thomas G. Re
Nassau Community College
What is Data
• Data is “a stream of facts that is not organized”
• Sometimes referred to as raw data, can not be
understood by people
• By Itself, in its raw form, cannot be used.
• Information: is when the raw data is organized in a
manner in which we could now understand and use.
• For Example
• A collection of addresses mean nothing. (They could be
Addresses of Employees, Customers, Suppliers, etc.)
Data and
Information Cont.
• When you place names and a description of the address,
• This now becomes meaningful information that can be
used.
• For example : Customer, Jill Smith 44 Oak Drive, Las
Vegas Nevada. This now becomes Information that is
useful.
• This Collection of Data shows the contrast between what
is Data and what is considered to be information.
• Databases : “is an ordered collection of related data
elements intended to meet the information needs of an
organization.
Databases
• In other words, databases are a collection of
information and data.
• Often the information and data are organized within
the databases according to how the data is related.
• How the data and information is related are
determined on business rules as well as the pure nature
of the data that is collected.
• Examples include: How personal customer
information may be related to reservations they have
made at a restaurant.
Databases Cont.
• Another example may be how products relate to each
other, i.e. Power tools versus Hand tools.
• Companies core business activities definitely pay a role
in how a database may need to be designed.
• The organization of the Data within a database is
often dictated by the Database Management system
that is used.
• With all the data and information that is collected
became the need of a Database Management system
software.
Databases
• There are many different types of databases.
• How they are organized are based on the models that are
chosen.
• Often the Database management System that is chosen, will
dictate the model in which is used to organize your data.
• These Models include
•
•
•
•
Hierarchical
Network
Relational
Object Oriented
Database
Management System
• A Database Management System (DBMS) is software that
helps organize, store, retrieve and edit meaningful data in a
database.
• Often is also responsible for providing security and access
rights to particular sections of the database.
• Provides a means to backup the data in the database
• Business rules, how data is collected and the data that is
collected may indicate the model that is used for organizing
your data and therefore may indicate the DBMS that needs
to be used.
• More about DBMS will be discussed later.
Database design
• Designing a database can be overwhelming and often
difficult to do.
• You need to first pick a good starting point to begin
organizing the data.
• In order to do this you need to understand the Data
Sources for the business.
• What data is collected,
• Find our how it is collected
• Find out how does the business use the data that is
collected.
Database Design
Cont.
• Often with the database design you need to pick a specific
starting point.
• A good place to start is by identifying the companies core
business rules.
• “primary activity”
• “reason for existence”.
• A sample of core business rules and organization include:
• Restaurant
• Make reservations
• Customer Orders of prepared food
• Supplies
• Making a distinction between dine in and dining out.
Database design
cont.
• Food supplies needed
• Suppliers used
• Of course even with this example, you may see that
there is still more aspects of the business that needs to
be included
• Again this is a starting point in which you can examine
a business, its collection of data and the rules of the
business that indicate the importence of the data that is
collected
Identifying primary
processes
• The core business of an organization typically is to
provide goods (i.e. a hardware store) or a service (i.e.
restaurant.
• Tasks that are needed to complete the process may be
one place to also start in examining the core business
rules of an organization.
• Identifying the core processes that are conducted in a
business may lead to finding data that may have been
overlooked, or exclude data from the design that was
not needed due to how the business is run.
Examining Specific
Data Sources
• Finding current Information
• Business documents and forms that are currently being
used is a good place to start
• Employee records. Records that are kept on current
employees of a business.
• Customer records Information collected about customers
• Company assets. What does the company own
• Inventory records. How is inventory kept and organized.
• Accounting records. Becomes very important for
collecting taxes as well as providing information on an
organizations financial resources.
Data sources cont.
• Finding Historic Information
• Historic information for an organization can be in both
electronic and paper form.
• The electronic form of this information can be in the form of a
spread sheet or an existing database that was poorly designed.
• In any case, gaps in the information that is examined can exist
due to lost, damaged or destroyed.
• Be careful not to dismiss data that is not useful due to age.
• Data mining software can often find relationships between old
records, and new records that may be collected.
Data Sources Cont.
• Using Human Resources
• Human resources becomes a great source on what
information of the employee is needed.
• Is job reviews or performances kept as a record?
• How about employee training opportunities?
• Records on employee certification and expiration dates
on the certification.
• Promotions and salary. How is this done?
• Income tax. This may be different from state to state and
therefore need specific data for employees working in
those states.
• Retirements
Data sources cont.
• Understand Data Flows and business rules and
processes.
•
•
•
•
Where data is collected
Where is it needed (what departments)
How is that data used?
Often data flows from multiple sources and collected for
one specific purpose. This type of flow of data is needed
to be identified.
• Often the flow of the data is needed to also be examined
in order to better understand the business as well as
understand the design of the database for that business.
Concerns with Data
collection
• Data Accuracy.
• Data Security
• Access security
• Physical security
• Managing data Organization
• Managing Data Access