RELATIONAL DATABASE MODEL

• Relational Data Model was first prosed by E. F. Codd of IBM in the 1970s. But, its commercial implementations were observed in the 1980s. The relational data model is employed for storing and processing the data in the database.
• Relational model in DBMS. In relational model, the data and relationships are represented by collection of inter-related tables. Each table isagroup of column and rows, where column represents attribute of an entity and rows represents records.

FEATURES OF RELATIONAL DATABASE MODEL:

• The database isaset of related relations (tables).
• Each relation has a name which indicates what type of tuples the relation has. For example,arelation named "Student' indicates that it has student entities in it.

• Each relation hasaset of attributes (column names) which represents, what type of information, the entities or tuples have? For example, Student relation hasaset of attributes Roll_No., Name, Department. It indicates that the Student relation has student entities/tuples that have information about their roll_no., name and department.

• A tuple (row) inarelation, is a real-world entity, it hasaset of values før corresponding attributes.

• Each data value in a row or tuple is called field.

• Each relation inadatabase must haveadistinct or unique name which would separate it from the other relations inadatabase.

• A relation must not have two attributes with the same name. Each attribute must haveadistinct name.

• Duplicate tuples must not be present in a relation.
• Each tuple must have exactly one data value for an attribute.
• Tuples inarelation do not have to followasignificant order as the relation is not order-sensitive.

• Similarly, the attributes ofarelation also do not have to follow certain ordering, it's up to the developer to decide the ordering of attributes.

• Each relation inadatabase must haveadistinct or unique name which would separate it from the other relations inadatabase.

• A relation must not have two attributes with the same name. Each attribute must haveadistinct name.
• Duplicate tuples must not be present in a relation.
• Each tuple must have exactly one data value for an attribute.
• Tuples inarelation do not have to followasignificant order as the relation is not order-sensitive.
• Similarly, the attributes ofarelation also do not have to follow certain ordering, it's up to the developer to decide the ordering of attributes.

ADVANTAGES OF RELATIONAL DATABASE MODEL:

• Structural Independence:The relational model does not depend on the navigational data access system, thus freeing the database designers, programmers and end users from learning the details of data storage changes in the database structure do not affect the data access.

• Conceptual Simplicity:The relational model frees the designer from the physical data storage details, the designer can concentrate on the logical view of the database.

• Design, Implementation&Uses are easy:The relational database model achieves botth data independence and structural independence making the database design, maintenance, administration and usage much easier than other model.

• Structured Query Language: Using SQL user can specify what information they want.

DISADVANTAGES OF RELATIONAL DATABASE MODEL:

• Hardware Overhead:Relational database system hides the implementation complexities and the physical data storage details from the users. For doing this, the relational database system needs powerful hardware computers and data storage devices.

• Ease of design can lead to bad design:The relational database is an easy-to-design and use system. Since the database is efficient but inefficiencies will not come to light when the database is designed or when there is onlyasmall amount of data.