logo chapter 5 understanding and designing accounting data king saud university noura al.madi 1

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Chapter 5 UNDERSTANDING AND DESIGNINGACCOUNTING DATA

King Saud University

Noura Al.Madi

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Contents

Introduction

Identifying and Documenting files

Attributes and Relationships

Developing UML Class Diagram

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Introduction

• Relational database: database in which data are represented as a set of two-dimensional tables with columns representing attributes and rows representing records

• Attributes: The smallest units of data that can have meaning to a user. The columns in a relational database that are equivalent to fields in a file.

Attribute (Filed)

Row (record)

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Identifying and Documenting Files

Transaction files: Used to record information about events in a business process.

Attributes include:– Transaction date– Agents associated with transaction– Description of products/services

associated with event

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Master files: • Store reference data • Store summary data

Events and transaction files:• First, identify the events in the business

process• Then, identify the need for transaction files in

the AIS

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UML class diagram:1.Shows relationships between

transaction and master files 2.Each box represents a file 3.Connecting lines between

files indicate file relationships 4.Can be used to document:

– Tables in an AIS– Relationships between

tables– Attributes of tables

Order

OrderOrder_Date

shipment

Invoice

Cash collection

Table (File) Name

Attributes (fields)

1m

Relationship

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Guidelines for identifying need for

transaction tables:1: Determine the events in the process 2: Exclude events that do not need to be

recorded in the computer system3: Exclude query and reporting events because

they involve using data that have already been recorded in the AIS

4: Exclude maintenance events

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Events and master tables:

• Typical master tables:– Products/services - master tables

•Describe products/services offered •Identify costs and/or prices of

products/services

– Agents - master tables describe•External agents •Internal agents

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– Cash - master file describes where cash is stored

– General ledger master file - needed if general ledger system is •Automated and•Integrated with the revenue or

acquisition cycle.Generally, master tables are used to store

relatively permanent data about an entity

(continued)

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Benefits of master tables:

• Save data entry time

• Save storage space

• Simplify making changes to data

• Simplify deleting transaction records

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Structure UML class Diagram (example)

General Ledger

Goods/ Service Events Agents

Order

Shipment

Invoice

Cash Collection

CustomerInventory

General Ledger

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- Agent associated with events on the right side of events.

- Goods/service associated with the event on the left side of the event.

- If required Cash Master File, it would be included in the table in the same column as the inventory.

- General Ledger master table to the left of goods/services.

- Arranging the transaction tables according to the sequence of events make it easier to read the diagram.

Guidelines

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Attributes And Relationships

Three important concepts:

1. Primary keys2. Linking attributes (foreign keys) 3. Relationship cardinalities

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This tables applies concepts:

Customer # Name AddressContact_Person Telephone #

3450 Brownsville C.C Brownsville, TX Smith 956-555-0531

3451 Educate, Inc. Fairhaven, MA Costa 508-888-4531

3452 Bunker Hill C.C Bunker Hill, MA Lanfranc 617-888-8510

Customer Table

Order # Order_Data Customer #

0100011 05/11/2003 3451

0100012 05/15/2003 3451

0100013 05/15/2003 3450

Order Table

Foreign keyPrimary key

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Primary key


1. Primary key:Attribute(s) that uniquely identifies a record in a table

2. Foreign key: A field in a table that is the primary key in

some other table– Used to link one table to another– Link event records to master records– Link two events that occur in a sequence

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3. Cardinality of the relationship:Cardinality is an expression of the relationship

between common fields (attributes) in two tables.

• Important in designing a database • Represents how many occurrences of one

type of entity are associated with another type of entity

• This relationship can be one-to-one (1,1), one-to-many (1,m), or many-to-many (m,m).

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One-to-one relationships (1,1) - not nearly as common as one-to-many relationships

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(continued)

Shipment Invoice

1 invoice per shipment

1 shipment per invoice

1 1

One-to-many relationships (1,m) - common in accounting systems

Order Customer

1 customer per order

many orders per customer over time

m 1


Many-to-many relationships (m,m) - can be converted into two one-to-many relationships by adding a “junction table”

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(continued)

Inventory Order

many orders per product over time

many product per order

m m

Inventory Order

many detail record per order; 1 order per detail record

1 product per detail record; many detail record per product

m mOrder Detail

1 1


Significance of concepts for database applications:

1. Implementing documents and reports2. Implementing input forms

– Input forms are used to make data entry more accurate/efficient

– Form designs rely on primary and foreign keys and relationships between tables

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3. Controlling AIS data – referential integrity– For one-to-many relationships we can specify

if we want referential integrity enforced on relationship

– Control most effective with two other controls:•Segregation of duties and•Access controls

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(continued)

Developing A UML Class Diagram

Example:Fairhaven convenience Store sells gasoline and other products. Customer select product and bring them to the manager. The manager scan the selected products, and the total amount due is displayed on the cash register. The customer give cash to the manager who puts it in the cash register. He gives change (if any) to the customer. Four managers work at the gas station, but only one manager is in the station at any one time. The manager who is in the third shift places the cash in an envelope and drops it in a deposit slot at the bank.

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Four basic steps in Developing A UML Class

DiagramStep 1: Place the required transaction tables (files)

on the UML class diagram.

A. Identify events in a business process.

B. Decide which events will need transaction tables.

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Event Is a transaction tables needed?

Make sale Yes, The sale and cash collection data should be record in the AIS.

Deposit cash Possibly. The company could record the data of the deposit, the amount, and the manager who made the deposit.


C. Start the UML class diagram by showing a box for each event requiring transaction tables

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(continue step 1)

sale

Deposit


Step 2: Place required master tables (files) on UML class diagram

A.For each event on the diagram (from Step 1), determine related goods, services, or agent entities

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Event Product/Service Internal Agent External Agent

Make sale Inventory Manager Customer

Deposit cash Cash Manager Bank Teller


B. Determine which identified entities require master tables.

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(continue step 2)

Two master table are needed:

Inventory Master TableManager Master Table

Not create master table for:

Customer: Customers names and address are not needed because the company will not bill customer since they must pay cash and no advertising will be sent to them.Bank teller: There is no need to identify the bank teller to whom a deposit is made.


C. Consider using master tables to track location of cash and effect of events on account balances in the general ledger

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The store does not need a master table for cash since all cash collections are deposited at the same bank.

Currently, the general ledger system is not automated, so no General_Ledger master table will be needed in the system.

(continue step 2)


D. Add required master tables to appropriate side of the UML class diagram

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Manager

Sale

Deposit

Inventory

(continue step 2)


Step 3: Determine required relationship between tables

A.For each connecting lines, determine cardinality of the relationship between tables

B.Write cardinalities next to line between entities

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m,1

Manager

Sale

Deposit

Inventory

m,1m,1

m,m


C. If there are any many-to-many relationships, convert them to one-to-many relationships by adding junction table (The junction table must include the primary keys of each of the tables in the many-to-many relationship)

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Manager

Sale

Deposit

Inventory

m,1m,1

Sales Detail

m,1

m,11,m

(continue step 3)


Step 4: Determine required attributes by:A.Assigning a primary key to each tables

B.Linking related tables by adding a foreign key to one of the pair in the relationship (Linking depends on cardinality of the relationship.

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Manager

Sale

Deposit

Inventory

(m,1)(m,1)Sales Detail

(m,1)(m,1)

(1,m)

Sale #SSN

SSN

Deposit #SSN

Sale #Product #

Product #


C. Assign other attributes as needed for providing information content

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Table Information attributes needed Primary Key Foreign Key

Manager Last_Name, First_Name, Address, Fill stats (tax filing status), Exemptions

SSN

Inventory Description, supplier, Reorder_Point, Quantity_on_hand

Product #

Sale Date, Sales_Tax Sale # SSN

Sale Detail Quantity_Sold, Price Sale #/Product #

Sale #/Product #

Deposit Date, Amount Deposit # SSN

(continue step 4)


Other Consideration in data design:

Simplifying the data design:1. One master table instead of two

If different tables have similar purposes and similar or identical structure

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Server

Customer

Take Order

CookPrepare

Meal


2. Eliminate redundant relationshipsDelete a line indicating a relationship between two tables if the relationship can be determined from others that occurred earlier.

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Order

Shipment

Customer

(continued)


3. One event table instead of twoIf there is a one-to-one relationship between events

in a sequence, the designer has the option

• Option A: Two records in two tables

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Rental_Transaction # Videotape # Data_Rented Customer #

1035 5220 05/14/2003 3201

Rentals Table (used to record rentals only)

Return_Transaction # Videotape # Data_Rented

1035 5220 05/14/2003

Return Table (used to record return only)

(continued)


• Option B: One record in one table

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Rental_Transaction # Videotape # Data_Rented Date_Returned

1035 5220 05/14/2003 05/17/2003

Rentals and Return Table

(continued)

4. Recording agent data in event tables


Communicating the data design:

Guidelines in preparing documentation:

1. Be consistent in naming entities2. Name boxes so can easily correlate UML

diagram with preceding documentation

3. Help reader understand how each part of the documentation relates to other parts

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Proper layout can also enhance readability

1. Start each part on a separate page 2. Clearly label each part 3. Write a brief explanation of the information

obtainable by reviewing diagram4. Use bulleted lists to explain linkages

between diagrams5. Use same style throughout

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LOGO

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logo chapter 5 understanding and designing accounting data king saud university noura al.madi 1

Documents

documenting files master

documenting files events

documenting files attributes

transaction tables

documenting files guidelines

documenting files agent

typical master tables

cash master file