Data Model is an abstract model that represents the data objects, data flow between these data objects, and the interrelationship between these data objects. It is a way of storing data on a computer so that it can be used in a more efficient manner for further purposes.
Data model or data structure consists of following fundamental elements:
1. Data object :
The data object is actually a location or region of storage that contains a collection of attributes or groups of values that act as an aspect, characteristic, quality, or descriptor of the object. A vehicle is a data object which can be defined or described with the help of a set of attributes or data.
Different data objects are present which are shown below:
- External entities such as a printer, user, speakers, keyboard, etc.
- Things such as reports, displays, signals.
- Occurrences or events such as alarm, telephone calls.
- Sales databases such as customers, store items, sales.
- Organizational units such as division, departments.
- Places such as manufacturing floor, workshops.
- Structures such as student records, accounts, files, documents.
2. Attributes :
Attributes define the properties of a data object. The attribute is a quality or characteristic that defines a person, group, or data objects. It is actually the properties that define the type of entity. An attribute can have a single or multiple or range of values as per our needs.
There are three types of attributes:
- Naming attributes –
To name an instance of a data object, naming attributes are used. User naming attributes identify user objects such as Login_names and User_Id for some security purpose. For example- Make and model are naming attributes in a vehicle data object.
- Descriptive attributes –
These attributes are used to describe the characteristics or features or the relationship of the data object. Sometimes also referred to as relationship attributes. For example- In a vehicle, the color of a data object is a descriptive attribute that describes the features of the object.
- Referential attribute –
These are the attributes that are used to formalize binary and associative relationships and in making reference to another instance in another table. For example- The data object is a referential attribute in a vehicle.
3. Relationship :
The relationship represents the connection or relation between different data objects and describes association among entities. Relationships are of three types: one-to-many, many-to-many, and many-to-one.
For example, toy and shopkeeper are two objects that share the following relationship:
- The Shopkeeper order toys.
- The shopkeeper sells toys.
- The shopkeeper shows toys.
- The Shopkeeper stocks toys.
In the above example, the type of relationship that is shown between shopkeepers and toys is one-to-many. ER Model is also used to represent the relationship between the data objects.
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