IMS1907 Database Systems

Summer Semester 2004/2005

Lecture 2

Relational DBMS Software An Overview of Microsoft Access

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Database applications are an intermediary between users and DBMSDBMS processes application requests against database– create definitions, write, read, update

Database Systems

Database Application

DBMS Database

Users

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Relational database systems are currently the most common used in industryAccess, SQL Server, Oracle, Ingres, DB2, Sybase, MySQL, Informix…Organises the database as groups of related tablesTables are organised by business ‘themes’– reflect practices and policies of organisation

Tables can be ‘joined’ to discover related information occurring across ‘themes’

Relational Database Systems

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Table– storage entity for a database– a grid made up of rows and columns– each row is a record– each column is a field– made up of records containing data about a ‘thing’

• customer, sale, rental, loan, supplier, product…– like a folder in a filing cabinet

Relational Database Terminology

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Record– unit within a table, normally a row of the table– contains related data about the entity

• a single transaction’s details, summary details,…– like a sheet of paper in a folder

Field– a smaller unit within a record, a column in the table– contains a single fact about the entity– like a field on a sheet of paper in a folder

Relational Database Terminology

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Keys– defined from one or more fields of a table– used to order, identify and retrieve data

Primary Key (PK)– a unique identifier for a particular record– no two records can share the same PK– often an ID number useful to a business

• customer number, student number, licence number,…

Relational Database Terminology

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Secondary Key – defined from one or more other fields of a a table – used to arrange database in some other order– can be multiple occurrences in a database

Foreign Key (FK)– one or more fields of a table that appear as a PK

in another table– can be multiple occurrences in a database– used to join tables based on common information

Relational Database Terminology

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Table Structure – metadata definitions– instructions regarding arrangement and format of

data in record– keys, data type, length– formats, masks, validation rules– constraints, rules

Relational Database Terminology

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Forms – alternative method to datasheet for entering and

accessing data– screen-based form appears similar to paper-based

equivalent of the record– can be used to both capture and display data– allow entry, editing, viewing and deletion of

records in one or more table

Relational Database Terminology

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Reports – provide the ability to arrange data from one or

more tables, and view and print the data for later use

– can also be used to perform calculations, summarise, and group information before viewing

– screen-based report can appear similar to paper-based equivalent of the report

– primarily a display mechanism only

Relational Database Terminology

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Queries – allow you to answer specific questions about data

in the database– can be used to display records based on criteria,

perform calculations, summarise information, sort and group information, or delete data from one or more tables in database

– can be regular or ad hoc

Relational Database Terminology

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Creating Access Tables

DB objects

existing DB objects

design options

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Creating Access Tables - Design View

properties

data type

data description

Primary key

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Access Tables – Datasheet View

datasheet

field names

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Sorting TablesUnsorted data

Data sorted by Member_No

Sort filters

Field to sort on

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Relationships Between Tables

edit relationship

related fields

relationship

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Subdatasheets

subdatasheet

Click ‘+’ to open subdatasheet

datasheet

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Access – Forms

formdatasheet

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Access – Forms and Sub-forms

form

sub-form

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Access – Queries

query design

related tables

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Access – Queries

query response

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Access – Reports

report design screen

table for report

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Access – Reports

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References

Duffy, T., (2000), Microsoft Access 2000, Prentice-Hall, Upper Saddle River, NJ, USA.

Kroenke, D.M., (2004), Database Processing: Fundamentals, Design and Implementation, (9th edn.), Pearson Education Inc., Upper Saddle River, NJ, USA.