Databases

Creating databases to store information

Learning Objectives

1. Explain what a database is, including common database terminology, and list some of the advantages and disadvantages of using databases.

2. Discuss some basic concepts and characteristics of data, such as data hierarchy, entity relationships, and data definition.

3. Describe the importance of data integrity, security, and privacy, and how they affect database design.

Understanding Computers: Today and Tomorrow, 14th Edition

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Learning Objectives

4. Identify some basic database classifications and discuss their differences.

5. List the most common database models and discuss how they are used today.

6. Understand how a relational database is designed, created, used, and maintained.

7. Describe some ways databases are used on the Web.

Understanding Computers: Today and Tomorrow, 14th Edition

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Breaking into database development

1. Analysis• Who will use it and

how?

2. Design• What data should it

have?• Should it have

forms?

3. Develop• Creation

4. Implement• Get rid of the “bugs”

5. Maintain• Keeping it running

From SDLC, break into DDLC

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2 What Is a Database?

A collection of related data stored in a manner so it can be retrieved as needed

Database management system (DBMS): A system used to create, maintain, and access

databases DBMSs include:

Personal Microsoft Access, Corel Paradox Lotus Approach

Enterprise databases Oracle Database IBM DB2 Microsoft SQL Server

Who uses databases?

Department of Motor Vehicles

Amazon – largest database on the Web

El Camino College

Search sites – Internet keyword search – Google, Bing, Yahoo! Search, Microsoft Live Search, Ask.com

60% of web page connections linked from search sites

Database Careers Individuals involved with a DBMS:

Database designers: Designs and creates the database and its objects

Database administrators: Responsible for managing the databases within an

organization Makes sure they have disk space Makes sure they are secure

Users: Individuals who enter data, update data, and retrieve

information out of the database

How does a database work?

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Databases and the WebDatabases are commonly used on the Web

Information retrieval, e-commerce, dynamic Web pages (change based on user input), etc.

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Database Hierarchy

Database: Contains a group of related tables

Tables: Contains collection of related records

Records(rows): Contains collection of related fields in a database (all the fields for one customer, for example)

Fields(columns): Single category of data to be stored in a database (name, telephone number, etc.)

Data(characters): letters, numbers, symbols

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Data Concepts and Characteristics

Relationships: Describe an association between two or more tables One-to-one (1:1) entity relationships (not

common) e.g. each school has one president and a president is

only at one school One-to-many (1:M) entity relationships (most

common) e.g. a employee earns one or more paychecks and each

paycheck is for only one employee Many-to-many (M:N) entity relationships (requires

a third table to tie the tables together) e.g. a teacher teaches one or more students and a

student has one or more teachers

Tables Relational databases arrange fields into structures

called tables Each table contains a collection of fields (columns) – each field is

a particular piece of information A set of related fields (collection of related information) is called a

record (row)

Relationships through Common fields Each table may relate to one or more other tables in the

database through common fields with common values.

Primary Keys Each record in a table should have a field/fields

which make that record unique and identifiable from the other records

Must have unique data (not duplicated)Must have data that doesn’t changeSpecial meaning in a relational database – it is used to connect 2 tables

Foreign Keys – how tables talk to each other

The common field in the related table is called a foreign key - it links to the primary key column(s) in another table, thereby creating a relationship.

Constraints Manage the REFERENTIAL INTEGRITY of the

data Cascade Updates and Cascade Deletes

Eliminates orphan records

Fine-tuning the database design Data definition: The process of describing the

properties of data to be included in a database table During data definition, each field is assigned:

Name (must be unique within the table) Data type (such as Text, Number, Currency, Date/Time) Description (optional description of the field) Properties (field size, format of the field, allowable

range, if field is required, etc.) Finished specifications for a table become the

table structure

Keeping it Meaningful Data integrity: The accuracy of data

Quality of data input determines the quality of retrieved information (GIGO)

Data validation: Ensuring that data entered into the database is valid Record validation rules: Checks all fields before changes

to a record are saved Can be enforced on a per transaction basis so the entire

transaction will fail if one part is invalid

Installing the Information System After all programs and database are created,

they are tested to make sure they work well together

“Information System” is then ready to be used

Wrapping it up• Large companies(like Amazon, Home Depot, Kaiser, etc.)

have an Integrated Enterprise type of Information System– Activities are designed to work together throughout the

enterprise– Enterprise Resource Planning (ERP) system

• Large integrated system that ties together all of a business’s activities

• Most common ERP systems are Inventory related – track and control inventory• Supply Chain Management (SCM) – reduce operating costs

while meeting delivery objectives • deliver the right product, to the right place, at the right time,

at the right price• Product Lifecycle Management (PLM) – manages a product as

it moves through its life cycle, from design, to development, to retirement

Wrapping it up• Information systems have a life cycle

(FADDIM)• Systems Analyst studies business problem

• uses tools such as ERD’s (entity-relationship diagrams), DFD’s (data flow diagrams) and DT’s (decision tree’s) to collect and analyze data

• Programmer develops software• Uses tools such as SDK’s (software development

kits) , API’s (application programming interfaces), flowcharts to help create the programs

Wrapping it up• It takes programs and data to make the

information system work• Objective: Business Intelligence through

data mining

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