Question

dentify the various types of data models and explain how they are useful in planning a database

Answer 1

There are basically two types of data model:

1. Record based data model
2. Object based data model

1) Record based data model

When the database is organized in some fixed format of records of several than the model is called record-based data model.

A fixed number of fields, or attributes in each record type and each field is usually of a fixed length. The three most popular record-based data models are,

(i) Relational data model

The relational data model uses tables to represent the data and the relationships among these data. Each table has multiple columns and each column is identified by a unique name. It is a low-level model.

Advantages of relational data model

• It is the simplest model at the conceptual level.
• The relational data model makes it easy to design, implement, maintain, uses the database.
• It does not affect the DBMS’s capability to access the data.
• The main reason for the popularity of relational model is the presence of powerful query capability.

(ii) Network data model

In the network data model, data model data are represented by collections of records. Relationships among data are represented by links. In this data model, graph data structure is used. It permits a record to have more than one parent.

Advantages of Network data model

• The Network data model is also conceptually simple and easy to design.
• In the network data model relationships like one-to-one and many-to-many are exist.
• In the network data model without the owner, no member exists.
• In the network database terminology, a relationship is a set. Each set comprises two types of record an owner record and a member record.

(iii) Hierarchical data model

In the hierarchical data, model data are represented by collections of records. Relationships among data are represented by links. In this model, tree data structure is used. There are two concepts associated with the hierarchical model segments types and parent-child relationships.

Advantages of Hierarchical data model

• Since the database is based on the hierarchical structure the relationships between the various layers are logically simple.
• The hierarchical data model was the first database that offered the data security that is provided by DBMS.
• The Hierarchical database model is based on the parent-child relationships.
• It is very efficient one when the database contains a large number of one-to-many relationships.

2) Object based data model

In the object-based data model, the database is organized in real-world objects of several types. A number of fields or attributes are defined in each object. The two most popular object-based data models are:

(i) Object oriented model

The object-oriented model is based on a collection of objects. An object contains values stored in instances variable within the object. An object contains bodies of code that operate on the object.

Advantages of object oriented data model

• It represents relationships explicitly supporting both navigated and associative access to information.
• Object-oriented database systems are not suited for all applications.
• It is difficult to maintain when organizational information changes.

(ii) ER (Entity Relational model)

The entity relational data model based on the perception of the real world that consist of a collection of basics objects and relationships between them. It is an object-based logical model. It is also high-level data model.