Download Database Overview

Overview
DATABASE DEVELOPMENT
Definitions
 A Database is a structured collection of related data
(not necessarily electronic)
 A Relational database is a database structure based
on tables linked by common (key) fields.
 A Database Management System (DBMS) is software
for managing one or more databases and providing
database functions such as backup and restore
 SQL is the language relational databases use for all
their functions including creating database objects,
retrieving, manipulating, inserting data, and for
administrative tasks
Definitions Continued
 A client application is software that uses the
database management system for its data
manipulation needs
 XML is a markup language that has become central
to the transfer and manipulation of data between
applications especially on the web.
Types of Databases
 Flat files—comma delimited text files or spreadsheet
programs like Excel
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Advantages: easy to understand and use
Disadvantages: data redundancy, data integrity issues, difficult
to manage as it becomes larger
 Hierarchical databases—structured like the file
system in windows
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Advantages: fast and easy to navigate
Disadvantages: data redundancy , difficulty comparing
different sets of data
Relational Databases
 Relational databases were designed to solve
problems in other types of databases
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Data Redundancy
Data integrity
Comparison of distinct sets of data
 The relational database design principles are based
on the mathematics of set theory.
 In a well designed database any piece of data can be
related to any other piece of data
Structure of Relational Databases
 Relational databases consist of tables. Each table
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represents one distinct aspect of the data.
Tables consist of columns and rows.
Columns contain the name of the data field
Rows contain the actual data
Tables are related by means of a common field
usually the “key” field of one table repeated in a
second table. (much more on this later)
Example
Department
Location
Phone
ACC
B2304
206.344.2001
HR
B2305
206.344.2020
EmployeeID
Lastname
Firstname
Department
20155
Larson
Sara
HR
90221
Town
Jason
ACC
30301
Manning
Patricia
ACC
32002
Adams
Tom
HR
Disadvantages of Relational Databases
 Relational database structure is complex. It is easy to
make a bad database
 Relational database require a lot of processing and
can be slow (Not as much of a problem with modern
machines)
DBMSs
 Access
 MySQL
 DB2
 SQL Server
 Oracle
Microsoft
MySQL
IBM
Microsoft
Oracle
SQL
 Everything that can be done in a Relational database
can be done in SQL
 SQL is a 4th generation language. That means you
code what you want to do not how.
SELECT LastName, FirstName, Phone, City
FROM Customers
WHERE City = ‘Seattle’
Client Applications
 Customers, most managers and business users don’t
want to work directly with the DBMS.
 Client applications are designed to allow users to
interact with the data in a more natural and
convenient way.
 Client applications can be written in a variety of
languages such as PHP, Java, C++, C#, Visual
Basic.Net and many others.
XML
 Xml is a markup language which has rapidly become
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important for transferring data between database
applications. (as well as for many other purposes)
XML is Operating System and Application Neutral.
As Text, it is safe and humanly readable
Most DBMSs can export data as xml and import xml
files into the databases
Some DBMSs such as SQL Server can store xml as a
native data type
XML Example
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<dataroot>
<customer>
<CustID>1</CustID>
<CustLastName>Jordan</CustLastName>
<CustFirstName>Mary</CustFirstName>
<CustAddress>2002 South Mercer Street</CustAddress>
<CustCity>Seattle</CustCity>
<CustState>WA</CustState>
<CustZipcode>98190 </CustZipcode>
<CustPhone>2065558828</CustPhone>
</customer>
<customer>
<CustID>2</CustID>
<CustLastName>Danner</CustLastName>
<CustFirstName>Thomas</CustFirstName>
<CustAddress>100 Boardwalk South</CustAddress>
<CustCity>Seattle</CustCity>
<CustState>WA</CustState>
<CustZipcode>98190 </CustZipcode>
<CustPhone>2065551001</CustPhone>
</customer>
<customer>
<CustID>3</CustID>
<CustLastName>Terrance</CustLastName>
<CustFirstName>Sarah</CustFirstName>
<CustAddress>202 Rt 3</CustAddress>
<CustCity>Bellevue</CustCity>
<CustState>WA</CustState>
<CustZipcode>98120 </CustZipcode>
<CustPhone>3605550128</CustPhone>
</customer>
</dataroot>