Data Objects, Attributes and Relationships in DBMS
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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