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Basic Definitions
Fundamentals of Data Base
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
InformationOutput
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Basic Definitions
DATA
A collection of incoming facts to the organization.
DATA-ITEM NAME
The context for a recorded data-item is often indicated by a name,
such as date, name, age, etc.
Incoming facts data
Data processing
InformationOutput
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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 ENTITYItems 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, ets.)
Attributes of car accident include items such as:
(driver-name, time, location, cause of accident, ets.)
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Basic Definitions
DATA-ITEM VALUE It is the specific quantitive or qualitive 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 quantitive.
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 qualitive.
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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
KEYIs an attribute or a set of attributes which the
computer uses to identify a record.
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Basic Definitions
KEYIs 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’, ets.
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Basic Definitions
KEYIs 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’, ets.
SECONDARY KEYIs a key which does not identify a unique record but which
identifies all those which have certain property.
Such as ‘DEPARTMENT-NAME’, ‘SKILL-CODE’, ets.
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Basic Definitions
Customer-id Customer-name
Customer-street
Customer-city
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 table
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Basic Definitions
Customer-id Customer-name
Customer-street
Customer-city
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 table
Data-item name
(Attributes)
(Fields)
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Basic Definitions
Customer-id Customer-name
Customer-street
Customer-city
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 table
Data-item name
Data-item value
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Basic Definitions
Customer-id Customer-name
Customer-street
Customer-city
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 table
Primary key
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Basic Definitions
Customer-id Customer-name
Customer-street
Customer-city
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 table
Primary key
Secondary key
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Basic Definitions
Customer-id Customer-name
Customer-street
Customer-city
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 table
Customer File
.
.
Reco
rds
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Basic Definitions
Summary: In this learning sequence, we discussed
the basic definitions related the subject “ Data Base “.
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Basic Definitions
END