Download Slides

Database
collection of related information stored in an organized form
Database program
software tool for storage & retrieval of that information.
Database Terminology
Data is held in tables
Record: one row in a a table
Field: columns that each record is divided into
Filing cabinet analogy
Database
(ABC Inc.)
Table
(Customers)
Record
(cust#78)
Field
(last name)
Relational Database
one-to-one relationship
table
EMPLOYEE TABLE
Id
001
002
003
004
...
Last
Name
Smith
Jones
Doe
Black
....
First
Name
Joan
Paul
John
Jason
....
WORK STATION TABLE
Work
Station
6-1942-A
9-0865-A
8-3649-B
8-3775-A
.......
Work
Station
6-1942-A
8-3649-B
8-3775-A
9-0865-A
........
Make and
Model
IBM-153
DELL-A14
IBM-153
HP-A919
........
key
EMPLOYEE
1
Operating
System
MS
Linux
MS
MS
......
record
1
WORK STATION
each employee has one workstation
Relational Database
EMPLOYEE TABLE
Id
001
002
003
004
...
Last
Name
Smith
Jones
Doe
Black
....
First
Name
Joan
Paul
John
Jason
....
one-to-many relationship
DEPARTMENT TABLE
Department
IT
MF
IT
HR
.......
Id
AR
IT
HR
MF
...
Name
Accounts Receivable
Information Technology
Human Resources
Manufacturing
....
....
.......
key
EMPLOYEE
*
1
DEPARTMENT
a department has many employees
an employee works in one department
Relational Database
many-to-many relationship
STUDENT TABLE
Id
001
002
003
004
...
Last
Name
Green
Black
Taylor
Trane
....
COURSE TABLE
First
Name
Jack
Millie
Peter
Oscar
....
key
Id
ASTB03
CSCA02
CSCA48
MTGA04
......
ENROLMENT TABLE
Name
Astronomy
The Why and How...
Programming
Management
........
Student Course
001
CSCA02
001
MTGA04
003
CSCA02
004
CSCA48
...... ........
STUDENT
COURSE
1
1
a student
takes many
courses
*
ENROLMENT
*
a course has
many students
Flat vs Relational
Flat
database system that performs operations on a single file
Relational
database system that has a number of different tables,
which may be linked together by common fields
Flat
Suppose you want to store information about books and their
authors
1st Solution:
Flat
2nd Solution:
both solutions: replication & data accuracy problems, wastes
space, data retrieval problems
Relational
Correct solution uses 2 linked tables
author’s name common to both tables
one-to-many relationship
∞
1
Primary Key
Every table should have a
primary key
– must be unique
– prevents duplicates
– maintains sort order (table
index)
– used to define
relationships
– may be a combination of
several fields
Good
Bad
SIN
Last Name
Employee ID
Address
Account #
Dept ID
User ID
Job Title
Email
any item that
could be
duplicated
Database Terminology
this is an Access Table:
Record
Field value
primary key
primary key
(every table needs one)
is used for
• sorting the table
• accessing individual
records
• linking tables
Form for entering records into a Table
Form for entering records into a Table
example of a Query on one Table
similar Query but showing only failing marks
similar Query, now modified
to include name and address from another Table
example of a Report based on a Table
example of a Report based on a Query
MS Access Environment
Menu Bar
Toolbar
Database Window
wizards
Object Buttons
tables
Status Bar
Creating a Table

Using Table Wizard

Designing a table yourself (using Design view)


field names

data types

primary key

properties
Views: Datasheet or Design

enter data using the Datasheet view
Design View
Primary Key
Field Names
Data Type
Description
Field
Properties
Data Types
Data Types
Text
Memo
Number
Date/Time
Currency
AutoNumber
Yes/No
OLE Object
Hyperlink
Properties
Properties
Field size
Format
Input Mask
Caption
Default Value
Validation Rule
Validation Text
Required
Allow Zero Length
Indexed
Datasheet View
• Use to add, edit, or delete records
Currently
selected record:
editing
 saved
End
Number of
current record
Total records
Relationships


ToolsRelationships…
Create a 1-to-many
relationship between
the CustomerID
fields
Relationships

One-To-Many relationship (Join)

a CustomerID can
appear once in
Customers and
many times in
Invoices
 a CustomerID in
Invoices must be in
Customers
Relationships

Enforcing Referential Integrity causes an error message if a
CustomerID not in the Customers table is entered
Indexes
• Examine indexes set
up for database
– make it faster to
search a table
– should be set up if
searching on a field is
anticipated
Note: indexing refers to
how data is stored,
whereas sorting changes
how the table is displayed.
Create a Form: wizard
• Form view
Form: Design view
sizing handles
drag
Toolbox
Form: complex example
Each page
shows one
record
Label
Text Box
(bound to field)
Command
Button