texas state technical college discover! database tables the building blocks of the relational...

Texas State Technical College

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Database TablesDatabase Tables

The building blocks of the relational database.


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Database Tables

The The tabletable is the basic structure of all is the basic structure of all relational databases. relational databases. One table represents One table represents one one type of objecttype of object in the real world in the real world domain.domain.

The table’s main purposes are:The table’s main purposes are:

• Define the object and all its attributesDefine the object and all its attributes

• Store all the instances of that object typeStore all the instances of that object type

Table PurposeTable Purpose


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Database Tables

Generic Object Type Generic Object Type (defined (defined byby the table) the table)• EngineEngine

Instances of the Engine Generic Type Instances of the Engine Generic Type (stored (stored inin the table) the table)• Ford 4 cylinderFord 4 cylinder• Ford V-6Ford V-6• Ford V-8Ford V-8• Dodge V-12Dodge V-12

Table Purpose IllustrationTable Purpose Illustration


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Database TablesTable CompositionTable Composition

Each table has two primary components.Each table has two primary components.

• Table DefinitionTable Definition• AttributeAttribute (field)(field)• Attribute type Attribute type (datatype)(datatype)• RelationshipRelationship (key)(key)

• Table DataTable Data• Instances Instances (records)(records)


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Database TablesTable DefinitionTable Definition

Defines the characteristics of one generic Defines the characteristics of one generic type of object.type of object.

The definition for a table is a list of pairs The definition for a table is a list of pairs {attribute name, attribute type}{attribute name, attribute type}

Any attribute/characteristic listed must be Any attribute/characteristic listed must be common to all objects of the object type.common to all objects of the object type.


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Database TablesTable Definition ExampleTable Definition Example

Name Volume Cylinders Max Torque Max RPM

Text Decimal Integer Integer Integer

[ ENGINE ]

Think of all the engines that exist or that you wish to model. The engine table describes a generic engine. It must define all the attributes that are common for all automotive engines. Below are only a few of the common characteristics/attributes in both a graphical and text based representation.

[ {Name, Text}, {Volume, Decimal}, {Cylinders, Integer}, {Max Torque, Integer}, {Max RPM, Integer} ]


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Database TablesTable DataTable Data

Stores all specific instances of the object Stores all specific instances of the object type.type.

Each instance or record represents one Each instance or record represents one existing or actual object of the object existing or actual object of the object type specified by the table.type specified by the table.

Each instance or record is a list of pairs Each instance or record is a list of pairs {attribute name, attribute value}{attribute name, attribute value}


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Database TablesTable Data ExampleTable Data Example


Ford 4 Cylinder 2.6 4 800 5200

[ ENGINE ]

Each instance of the object type is referred to as a record. Each record is visualized as below in two different ways, as graphical and as text. There are two records, one describing a Ford 4 cylinder engine and the other a Ford V-6 engine.


Ford V-6 3.6 6 1400 7200

[ {Name, Ford 4 Cylinder}, {Volume, 2.6}, {Cylinders, 4}, {Max Torque, 800}, {Max RPM, 5200} ]

[ {Name, Ford V-6}, {Volume, 3.6}, {Cylinders, 6}, {Max Torque, 1400}, {Max RPM, 7200} ]

RECORD #1

RECORD #2


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Database TablesTable CompositionTable Composition


Text Decimal Integer Integer Integer

Ford V-6 3.6 litre 6 1400 7200

Ford 4 Cylinder 2.6 litre 4 800 5200

[ ENGINE ]

When we combine the two components, we get something most of us are a little more used to seeing. It is a lot like an Excel spreadsheet, except in a table all the cells or fields in a row are related because they describe one actual object.

DEFINITION

DATA


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Database TablesIn Summary…In Summary…

• The two basic components of tables are the table The two basic components of tables are the table definitiondefinition and the table and the table datadata..

• Relational databases define Relational databases define object typesobject types and store and store occurrences of that object type through the use of occurrences of that object type through the use of tables.tables.

• Tables are composed of Tables are composed of fields fields and and recordsrecords..

• Fields are used to define the Fields are used to define the attributes attributes of an object of an object type.type.

• Records are used to store individual occurrences or Records are used to store individual occurrences or instancesinstances of an object type. of an object type.

texas state technical college discover! database tables the building blocks of the relational...

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