Basic Definitions Fundamentals of Databases

Dr. Rashid Al_Zubaidy

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.

Basic DefinitionsDATA

A collection of incoming facts to the organization.

Incoming factsdataData processingInformationOutput

Basic DefinitionsDATA

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 factsdataData processingInformationOutput

Basic DefinitionsGROUP 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).

Basic DefinitionsAn 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.

Basic DefinitionsAN 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.)

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 its qualitative.

Basic DefinitionsRECORD

Is a collection of related data-item which share a common context about a particular entity.

Basic DefinitionsRECORD

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.

Basic DefinitionsENTITY 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.

Basic DefinitionsENTITY 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.

Basic DefinitionsENTITY 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.

Basic DefinitionsENTITY 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.

Basic DefinitionsKEY

Is an attribute or a set of attributes which the computer uses to identify a record.

Basic DefinitionsKEYIs an attribute or a set of attributes which the computer uses to identify a record.

PRIMARY KEYIs defined as that key used to uniquely identify one record. Such as STUDENT-NUMBER, EMPLOYEE-ID, etc.

Basic Definitions

CUSTOMER table

Customer-idCustomer-nameCustomer-streetCustomer-city192-83Ahmed23 Alma St.Jbeha182-74Kasim12 Main St.Sweleh677-600Rana7 Park Ave. Marka321-140Susan57 North St.Jabal710-569Tarik33 Alma St.Jbeha210-872Ali88 East St.Gardens

Basic Definitions

CUSTOMER table

Data-item name(Attributes)(Fields)

Customer-idCustomer-nameCustomer-streetCustomer-city192-83Ahmed23 Alma St.Jbeha182-74Kasim12 Main St.Sweleh677-600Rana7 Park Ave. Marka321-140Susan57 North St.Jabal710-569Tarik33 Alma St.Jbeha210-872Ali88 East St.Gardens

Basic Definitions

CUSTOMER table

Data-item nameData-item value

Customer-idCustomer-nameCustomer-streetCustomer-city192-83Ahmed23 Alma St.Jbeha182-74Kasim12 Main St.Sweleh677-600Rana7 Park Ave. Marka321-140Susan57 North St.Jabal710-569Tarik33 Alma St.Jbeha210-872Ali88 East St.Gardens

Basic Definitions

CUSTOMER table

Primary key

Customer-idCustomer-nameCustomer-streetCustomer-city192-83Ahmed23 Alma St.Jbeha182-74Kasim12 Main St.Sweleh677-600Rana7 Park Ave. Marka321-140Susan57 North St.Jabal710-569Tarik33 Alma St.Jbeha210-872Ali88 East St.Gardens

Basic Definitions

CUSTOMER table

Customer File..Records

Customer-idCustomer-nameCustomer-streetCustomer-city192-83Ahmed23 Alma St.Jbeha182-74Kasim12 Main St.Sweleh677-600Rana7 Park Ave. Marka321-140Susan57 North St.Jabal710-569Tarik33 Alma St.Jbeha210-872Ali88 East St.Gardens

Basic Definitions Summary: In this learning sequence, we discussed the basic definitions related the subject database.

Basic Definitions

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