COMM 205 Unit 5

Question 1

Why Businesses Use Database?

Answer 1

Businesses need information to run their operations
 What are the sales from June?
 When will people come into our stores?
 Who are our employees? How much should they be paid?

Question 2

Storing Transactional Data

Answer 2

Transactional data is stored in databases.
DATABASE – a collection of records about various business categories (entities) such as:
 resources (inventory)
 events (sales, payroll)
 people (employees, customers)  places (warehouses, stores)
 INFORMATION SYSTEMS maintain and access the transactional DATA in databases.

Question 3

Business Data Management questions

Answer 3

Who would give us this information?
How can we ensure that it is accurate?
Some of what we are talking about is DATA and not INFORMATION.
How do we get the hard-to-find data?
For instance, how do we get certain types of customer
information?

Question 4

Importance of Managing Data

Answer 4

An effective information system provides  Timely Information
 Quality Information
 Relevant Information
DATA a should be stored and managed efficiently in electronic storage devices.
DATABASES are efficient ways to do this.

Question 5

What is the big deal about putting data into a database?

Answer 5

How can you ensure that
 there is no data redundancy?  data can be shared?
o Also,howcandatabesharedinawaythatitdoesnot violate privacy and confidentiality?
 there is data consistency (or data integrity)?

Question 6

Problems with Traditional File-Based Systems

Answer 6

Data Redundancy
 Duplicate data in multiple data files.
 Wastage of storage space and inefficient processing.
Data Inconsistency
 Various copies of the data do not agree.
 Different representations of the same piece of data in different places.
Data isolation
 Applications cannot access data associated with other
applications.

Question 7

What is a Database?

Answer 7

A DATABASE is an organized collection of logically related data.
A DATABASE MANAGEMENT SYSTEM (DBMS) is the software used to
 Reduce data redundancy;
 Share data in a controlled way; and  Reduce data integrity problems.
A DATABASE is a STRUCTURED collection of data accessed and utilized by many different applications and users.

Question 8

Definition: Database Management Systems

Answer 8

Database Management Systems (DBMS) – software through which users and application programs interact with a database.
Software used to create, manage, maintain, and manipulate a database.

Question 9

Examples of DBMS

Answer 9

Microsoft Access
Microsoft SQL Server
 Oracle
MySQL (open source database)
IBM DB2
FileMaker Pro (a subsidiary of Apple Inc.)

Question 10

Benefits of DBMS

Answer 10

Data Security
 Databases have high security measures in place to deter mistakes and attacks.
Data Integrity
 Data meet certain constraints, such as no alphabetic characters in a Social Insurance Number field.
Data Independence
 Applications and data are not linked to each other, so
that all applications are able to access the same data.

Question 11

Data Hierarchy

Answer 11

Logical view:
Database File (Table)
A logical grouping of related files.
File (Table
A logical grouping of related records.
Record
A logical grouping of related fields.
Field
A single fact or attribute of something.

Physical view:
Byte
Represents a single character
Bit
(Binary digit) Represents the smallest unit of data a computer can process.

Question 12

Relational Databases: Table

Answer 12

Data organized as two-dimensional tables.
 Table (File)
 Row (Record)
 Column (Field or Attribute)
Primary key : field(s) whose value uniquely identifies each row
Each table must have a PRIMARY KEY that uniquely identifies each row.
 Composite primary key
o A primary key that consist of more than one field
 Atomic primary key
o A primary key that consist of only one field

Question 13

Relational Databases: Linking Tables

Answer 13

Collection of logically linked (related) Tables
Tables are linked by matching fields
Primary Key and Foreign Key are used to create logical relationships between tables
 Primary Key is an attribute that uniquely identities each record in a table (parent table).
 Foreign Key is an attribute in a table (child table) that REFERENCE A PRIMARY KEY OF THE PARENT TABLE.

Question 14

Integrity Constraints

Answer 14

Entity Integrity:
 (1) unique value (2) no Null value in PRIMARY KEY field
Referential Integrity:
 A FOREIGN KEY may have either (1) a Null value, or (2) a value that matches a value in the primary key of a linked (PARENT) table

Question 15

Why do we need to normalize databases?

Answer 15

The main purpose of NORMALIZATION is to reduce duplication of data.

Question 16

Database Queries

Answer 16

Structured Query Language (SQL)
SQL enables people to perform complicated searches by using relatively simple statements such as SELECT (the attribute), FROM (table to be used) and WHERE (specify conditions). For example,
Query by Example (QBE)
Allows users to fill out a query design grid or template to construct a sample or description of the data he or she wants

Question 17

Conclusion

Answer 17

A database stores and maintains DATA and information.
 The database management system (DBMS) is the SOFTWARE used to handle the storage, retrieval and updating of data in a database.
 The database approach minimizes the following major problems: DATA REDUNDANCY, DATA INCONSISTENCY, AND DATA ISOLATION.