Transcript S1

Basic Definitions
Fundamentals of Databases
Dr. Rashid Al_Zubaidy
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Basic Definitions
Welcome: The first learning sequence
“ Basic Definitions “
Present learning: We shall explore the following
definitions:
- Data-item name and value.
- Key identifier.
- Record and File.
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Basic Definitions

DATA
A collection of incoming facts to the
organization.
Incoming facts
data
Data
processing
Information
Output
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Basic Definitions

DATA
A collection of incoming facts to the
organization.
Incoming facts
data
Data
processing
Information
Output
DATA-ITEM NAME
The context for a recorded data-item is often
indicated by a name,
such as date, name, age, etc.
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Basic Definitions

GROUP ITEMS AND ELEMENTRY
ITEMS
A group item is a collection of closely related items of
information.
For example DATE usually have three parts,
MONTH, DAY, YEAR, when any of there have no
farther subdivision into meaning full parts they are
called ELEMENTRY data-item else the called
GROUP data-item or (Aggregate).
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Basic Definitions

An ENTITY
Items about which we store information are referred
to as Entities.
An Entity may be Tangible object such as:
A person (Employee), place (Amman), or thing (parts)
An Entity may be Non Tangible, such as:
An event (something happens at a particular time),
customer-account, etc.
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Basic Definitions
AN ATTRIBUTE
An Entity has various properties which we may wish to
record, so that we can recognize, remember, and describe it.
These properties are called Attributes. For example:
Attributes of human being include items such as:
(height, weight, name, age, eye color, etc.)
Attributes of car accident include items such as:
(driver-name, time, location, cause of accident, etc.)
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Basic Definitions
DATA-ITEM VALUE
It is the specific quantative or qualitative values given to a
specific data-item.
For example: If ‘AGE’ is an attribute of some entity
and it is equal to ’22’, then 22 is the related data value and it
is quantative.
And if ‘CITY’ is an attribute of some entity and it is
‘Baghdad’ then ‘Baghdad’ represent the data item value for
data-item name CITY, and it’s qualitative.
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Basic Definitions

RECORD
Is a collection of related data-item which share a
common context about a particular entity.
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Basic Definitions

RECORD
Is a collection of related data-item which share a
common context about a particular entity.

FILE
A file may be defined as a set of (Logical) records
all of which related to a particular area of interest.
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Basic Definitions
ENTITY IDENTIFIER
It is necessary for the programmer or data
administrator to be able to refer to a record
relating to a given entity, and it is necessary for the
computer to be able to identify it and have a means
of finding it in the storage unit. For this purpose
one of the attributes is usually designated an entity
identifier.
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Basic Definitions
ENTITY IDENTIFIER
It is necessary for the programmer or data administrator
to be able to refer to a record relating to a given entity, and
it is necessary for the computer to be able to identify it and
have a means of finding it in the storage unit. For this
purpose one of the attributes is usually designated an entity
identifier.
For example the entity identifier of an employee would
be
EMPLOYEE-NUMBER.
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Basic Definitions
ENTITY IDENTIFIER
It is necessary for the programmer or data administrator to be able to
refer to a record relating to a given entity, and it is necessary for the
computer to be able to identify it and have a means of finding it in the
storage unit. For this purpose one of the attributes is usually designated
an entity identifier.
For example the entity identifier of an employee would be
EMPLOYEE-NUMBER.
And the entity identifier of an account record would be the
ACCOUNT-NUMBER.
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Basic Definitions
ENTITY IDENTIFIER
It is necessary for the programmer or data administrator to be able to refer to
a record relating to a given entity, and it is necessary for the computer to be able
to identify it and have a means of finding it in the storage unit. For this purpose
one of the attributes is usually designated an entity identifier.
For example the entity identifier of an employee would be
EMPLOYEE-NUMBER.
And the entity identifier of an account record would be the
ACCOUNT-NUMBER.
Some time more than attribute is required in order to identify a record.
For example, to identify an airline flight record the FLIGHT-NUMBER
and FLIGHT-DATE are needed.
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Basic Definitions

KEY
Is an attribute or a set of attributes which the
computer uses to identify a record.
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Basic Definitions

KEY


Is an attribute or a set of attributes which the
computer uses to identify a record.
PRIMARY KEY

Is defined as that key used to uniquely identify
one record. Such as ‘STUDENT-NUMBER’,
‘EMPLOYEE-ID’, etc.
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Basic Definitions
CUSTOMER table
Customer-id
Customername
Customerstreet
Customercity
192-83
Ahmed
23 Alma St.
Jbeha
182-74
Kasim
12 Main St.
Sweleh
677-600
Rana
7 Park Ave.
Marka
321-140
Susan
57 North St.
Jabal
710-569
Tarik
33 Alma St.
Jbeha
210-872
Ali
88 East St.
Gardens
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Basic Definitions
CUSTOMER table
Data-item name
(Attributes)
(Fields)
Customer-id
Customername
Customerstreet
Customercity
192-83
Ahmed
23 Alma St.
Jbeha
182-74
Kasim
12 Main St.
Sweleh
677-600
Rana
7 Park Ave.
Marka
321-140
Susan
57 North St.
Jabal
710-569
Tarik
33 Alma St.
Jbeha
210-872
Ali
88 East St.
Gardens
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Basic Definitions
CUSTOMER table
Data-item name
Data-item value
Customer-id
Customername
Customerstreet
Customercity
192-83
Ahmed
23 Alma St.
Jbeha
182-74
Kasim
12 Main St.
Sweleh
677-600
Rana
7 Park Ave.
Marka
321-140
Susan
57 North St.
Jabal
710-569
Tarik
33 Alma St.
Jbeha
210-872
Ali
88 East St.
Gardens
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Basic Definitions
CUSTOMER table
Primary key
Customer-id
Customername
Customerstreet
Customercity
192-83
Ahmed
23 Alma St.
Jbeha
182-74
Kasim
12 Main St.
Sweleh
677-600
Rana
7 Park Ave.
Marka
321-140
Susan
57 North St.
Jabal
710-569
Tarik
33 Alma St.
Jbeha
210-872
Ali
88 East St.
Gardens
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Basic Definitions
CUSTOMER table
Records
.
.
Customer-id
Customername
Customerstreet
Customercity
192-83
Ahmed
23 Alma St.
Jbeha
182-74
Kasim
12 Main St.
Sweleh
677-600
Rana
7 Park Ave.
Marka
321-140
Susan
57 North St.
Jabal
710-569
Tarik
33 Alma St.
Jbeha
210-872
Ali
88 East St.
Gardens
Customer File
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Basic Definitions
Summary: In this learning sequence, we discussed the
basic definitions related the subject “database“.
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Basic Definitions
END
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