Lecture Accounting information systems: Chapter 4 - Richardson, Chang, Smith

Chapter 4
Relational
Databases
and
Enterprise
Systems
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Learning Objectives
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LO#1 Describe the advantages of relational databases.

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LO#2 Explain basic relational database principles.

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LO#3 Describe how to query using Structured Query
Language (SQL).
LO#4 Understand the purpose and basic framework for
an enterprise system.
LO#5 Assess how cloud computing facilitates enterprise
systems

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LO# 1

Introduction of Database
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A database is a collection of related data
for various uses.
Three types of data models:

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A Hierarchical data model organizes data
into a tree-like structure that allows
repeating information using defined
parent/child relationships.
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LO# 1

Introduction of Database
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Relational data models are the dominant data model
form in use today likely because they offer many
advantages over other data models, including:

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Flexibility and Scalability

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Simplicity

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Reduced Information Redundancy

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LO# 2

Definitions for Databases
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Database Management System (DBMS) – The DBMS
is defined as a computer program that creates, modifies
and queries the database. Specifically, the DBMS is
designed to manage a database’s storage and retrieval
of information.
Data Dictionary – The data dictionary describes the

data fields in each database record such as field
description, field length, field type (e.g., alphanumeric,
numeric), etc.
Database Administrator – The person responsible for
the design, implementation, repair and security of a
firm’s database.
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LO# 2

Fundamentals of Relational Databases
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Entities and Attributes:
A class in the relational database model could be a
person, place, thing, transaction, or event about which
information is stored. Classes could be grouped into
resources (R), events (E), and agents (A) in data
modeling.
Attributes are characteristics, properties, or adjectives
that describe each class.

Keys and Relationships:
A primary key is an attribute or combination of attributes
that uniquely identify a specific row in a table.
4-6 serves as
A foreign key in the relational database model


LO# 2

Fundamentals of Relational Databases
•
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Three Main Constructs
Table/Relation: The primary construct, used for data
storage with rows and columns much like a spreadsheet.
Each table in a database represents either a class or a
relationship between classes. Tables need to be
properly linked to make a relational database.
Column: The columns in a table are called fields that
represent the attributes or characteristics of the class or
relationship.
Rows: The rows in a table are called records or tuples.
The records represent all the specific data values that
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are associated with one instance.


LO# 2

Fundamentals of Relational Databases
•
•

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Basic Requirements of Tables
The Entity Integrity Rule: the primary key of a table
must have data values (cannot be null).
The Referential Integrity Rule: the data value for a
foreign key must either be null or match one of the data
values that already exist in the corresponding table.

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LO# 2

Fundamentals of Relational Databases
•
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Basic Requirements of Tables
Each attribute in a table must have a unique
name.
Values of a specific attribute must be of the
same type.
Each attribute (column) of a record (row) must
be single-valued. This requirement forces us to
create a relationship table for each many-tomany relationship.
All other non-key attributes in a table4-9
must


LO# 2

Microsoft Access to Implement a
Relational Database
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Introduction to Microsoft Access

Access is a simple database management system that
can be used to run databases for individuals and small
firms.
The Access system is composed of seven objects that
are used to implement relational databases.
----Tables are used to store data which consists of a series
of rows (records) and columns (attributes) connected by

relationships (links between tables).
----Queries are a tool used to retrieve and display data
derived from records stored within the database.
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LO# 2

Microsoft Access to Implement a
Relational Database
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Reports are used to integrate data from one or more
queries and tables to provide useful information to
decision makers.
Pages, Web-based forms, allow data to be entered into
the database in real time from outside of the database
system.
Macros are defined by users to automate processes like
opening a specific form.
Access’s code can be altered by the use of modules.

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LO# 3

Structured Query Language (SQL)
•

•

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SQL (usually pronounced "Sequel") stands for
Structured Query Language and is a computer
language designed to query data in a relational
database.
SQL is based on relational algebra and allows a user to
query and update the database.
In a database, while queries allow the user to access,
read and report on desired data, the responsibility of
actually making physical changes to the relational
database belongs to the Database Management
System (DBMS).
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LO# 3

Structured Query Language (SQL)
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The SELECT statement is used to begin
a query.
The SELECT statement tells the query
which columns (or attributes) of a table
should be included in the query
The FROM clause to the SELECT
statement indicates the name of table(s)
from which to retrieve data.

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LO# 3

Structured Query Language (SQL)
•

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The WHERE clause states the criteria that
must be met to be shown in the query
result.
The GROUP BY operator is used with
aggregate functions on the query results
based on one or more columns.

The ORDER BY clause identifies which
columns are used to sort the resulting data.
If there is no ORDER BY clause, the order
of rows returned by an SQL query will not
be defined.
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LO# 3

Structured Query Language (SQL)
•

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The INSERT INTO operator inserts data into a
SQL table.
The UPDATE operator is for updating data in a
SQL table.
The DELETE FROM operator deletes data from
a SQL table.
SELECT DISTINCT clause selects a column

without showing repetitive values.
The BETWEEN operator can be used to specify
the end points of a range.
Membership Operator (IN) allows you to test
whether a data value matches the specified
target values.
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LO# 3

Structured Query Language (SQL
Six relational operators in SQL
Relational Operators

Meaning

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=

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!= or <>

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<

less than

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<=

less than or equal to

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>

greater than

>=
to

greater than or equal

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equal
not equal

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LO# 3

Structured Query Language (SQL
SQL language provides several convenient

aggregate functions to be used in SQL commands.
These aggregate functions include AVG, SUM,
MAX, MIN, and COUNT. Their definitions are as
follows:
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AVG(X): gives the average of column X.
SUM(X): gives the summation of all rows that
satisfy the selection criteria for column X.

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MAX(X): gives the maximum value of column X.

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MIN(X): gives the minimum value of column
X.
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LO# 4

Enterprise Systems
Enterprise systems (ES), also known as Enterprise
Resource Planning (ERP) systems, are commercialized
information systems that integrate and automate business
processes across a firm’s value chain located within and

across organizations. Typically, an enterprise system uses
relational data model as a basis for the information
system. The use of primary and foreign keys links the
hundreds of tables that form the basis for the enterprise
system.
In fact, for a popular ERP product (SAP/ERP) installation, there are
10,000 tables that are all linked to each other!
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LO# 4

Enterprise Systems
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ES accommodates the integration and support of the
various business processes and information needs of a
company.
ES has a higher level of internal transparency compared
to the typically isolated legacy systems.
The purported informational benefits of an enterprise
system include enhanced completeness, transparency,
and timeliness of information needed to manage
effectively an organization’s business activities.

The enterprise system serves as the backbone of the
company’s internal business processes and serves as a
connection with the external business processes
for
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LO# 4

Enterprise Systems
Challenges of Enterprise System Implementation
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integrating various modules within the enterprise system,
integrating with external systems such as the information
system of a supplier and/or customer,
integrating with the firm’s own existing legacy systems,
converting data from existing legacy systems to the
enterprise system, and
getting any big project implemented at a firm.

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LO# 5

Enterprise Systems
Enterprise Systems Computing in a Cloud
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In recent years, cloud computing has emerged as a
potential alternative to host enterprise systems and other
firm computing needs.
Cloud computing is Internet-based computing where
shared resources, software, and information are
provided to firms on demand.
Cloud Computing can easily host enterprise system
applications.
Cloud computing, of course, has disadvantages as
well. Ensuring that any sensitive data is secure and
backed up frequently by the host is often a 4-21
concern of