DATABASE DESIGN

Using Access 2007

ACCESS 2007 DMS

Database management system Database

Collection of data organized in a manner that allows access, retrieval, and use of that data.

--- OR ---A place to store data and retrieve

information

ACCESS OBJECTS… Tables

Like ExcelEnter, edit, and delete dataDisplay, sort and filter

QueriesAsk questions and get answers from data

ReportsPrint customized displays of data

FormsVisualCan limit data by user

TABLES Each row is a separate record, or an entry in

the database One customer One order

Each record has a unique identifier, called a primary key, such as:

Customer ID Student ID SSN

Each column is a field Name, address, phone number Item number, quantity ordered

THE KEY To designing a good database ….

A good plan

NORMALIZING DATA Table designs should eliminate redundant

(repeating) data. This is called normalizing a database.

Customer names and addresses would be listed in a separate table, and not included with every order the customer makes

Students’ names and address are in a separate table, and not included with their schedule and grade information

More info on database design for Access 2007 is available here.

STEPS FOR DESIGNING TABLES1. Decide what tables to including in your

database. An online clothing store might include:

Product inventory Item number, Item name, purchase price, number in

stockVendors (the people you buy from)

Vendor number, vendor name, address, city, state, zip, terms

Customers (the people you sell to) Customer number, customer, name, address, city, state,

zip, phone numberOrders

Customer number, item number, quantity

STEPS FOR DESIGNING TABLES2. Choose a primary key for each table3. Format the data for each field

Text or numbers Maximum number of characters Required or not?

4. Security – who will have access5. Set relationships between tables

COMMON ACCESS DATA TYPES Text fields (default)

May contain letters, numbers, and symbolsMaximum 255 characters

Number fieldsMay contains ONLY numbersCan be positive or negativeCan be used for arithmetic operations

Currency fieldsMay contain ONLY monetary dataWill display like currency formatting in ExcelCan be used in arithmetic operations

NUMBER FIELDS Byte: Integer from 0 to 255 Integer: Integers from -32,768 to 32,767 Long Integer: Integers from -

2,147,483,648 to 2,147,483,647. Single: Numbers with up to 7 decimal

places Double: More decimal places; 2x the

storage Decimal: More decimal places; 3x the

storage Replication ID: Special identifier required

for replicationChoose the smallest size you can for your

data

OTHER ACCESS DATA TYPES Memo

Up to 63,999 characters Date/Time AutoNumber

Stores a unique sequential number for each record

Values CANNOT be re-used Yes/No

Values can be Yes/No, True/False, or On/Off OLE Object Hyperlink Attachment

Images, spreadsheets, etc.

RELATIONSHIPS Relationships exists between tables One-to-many (most common)

Each customer has many ordersEach student has many classesEach employee has many paychecks

One-to-oneEach customer has one addressEach student has one lockerEach employee works for one department

Many-to-many (least common)

FACTS ABOUT ACCESS 2007 Field names

Can have up to 64 charactersCan contain letters, numbers, characters

and spaces EXCEPT Periods (.) Exclamation points (!) Accent graves (`) Square brackets ([ and ])

USING ACCESS Some things about Access are different

from other Office applicationsAll tables, queries, forms and reports are

stored in the same fileWhen you start a new database, you have to

name it before you can create any tablesAccess saves database files with an .accdb

extensionWhen you enter data, each record is

automatically saved when you move to the next

If you delete a record or a table field, it gone for good.

THE ACCESS WINDOW