Data modeling

Data Modeling
• Requirements modeling includes many sub-stages, one
of them being data modeling.
• Once a use case exists, one of the stages that follow will
be data modeling.
• Data modeling, sometimes also called information
modeling, is the process of visually representing what
data the application or system will use, and how the
data will flow.

Data Modeling
• The fundamental elements that a data model needs to include
and describe are the data objects, more frequently
called 'entities', the attributes of those objects/entities, and
the relationships between the objects/entities.
• The two most widely used are UML (Unified Modeling Language),
and ERD (Entity-Relationship Diagrams).
• The software engineer defines all the data object that proceeds
within the system and the relationship between data objects are
identified.

Data Object
• The data object is the representation of composite information.
• The composite information means an object has a number of different
properties or attribute.
• For example, Height is a single value so it is not a valid data object, but
dimensions contain the height, the width and depth these are defined
as an object.
• Data Entity /Object
• An entity is something that exists as itself, as a subject or as an object,
actually or potentially, concretely or abstractly, physically or not.
• Data Attributes
Each of the data object has a set of attributes.
• Relationship
Relationship shows the relationship between data objects and how
they are related to each other.
• Cardinality
Cardinality state the number of events of one object related to the
number of events of another object.

Cardinality
 The cardinality expressed as:
One to one (1:1)
One event of an object is related to one event of another
object.
For example, one employee has only one ID.
One to many (1:N)
One event of an object is related to many events.
For example, One collage has many departments.
Many to many(M:N)
Many events of one object are related to many events of
another object.
For example, many customer place order for many
products.

Data modeling

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