RELATIONAL DBMS

RDBMS  (relational database management system)

RDBMS stands for Relational Database Management System. RDBMS is the basis for SQL, and for all modern database systems like MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access.

A Relational database management system (RDBMS) is a database management system (DBMS) that is based on the relational model as introduced by E. F. Codd.

A relational database management system (RDBMS) is a collection of programs and capabilities that enable IT teams and others to create, update, administer and otherwise interact with a relational database. RDBMSes store data in the form of tables, with most commercial relational database management systems using Structured Query Language (SQL) to access the database. However, since SQL was invented after the initial development of the relational model, it is not necessary for RDBMS use.

RDBMS stands for relational database management system. A relational model can be represented as a table of rows and columns. A relational database has following major components:
1. Table
2. Record or Tuple
3. Field or Column name or Attribute
4. Domain
5. Instance
6. Schema
7. Keys

1. Table

A table is a collection of data represented in rows and columns. Each table has a name in database. For example, the following table “STUDENT” stores the information of students in database.

Table: STUDENT

Student_Id	Student_Name	Student_Addr	Student_Age
101	Chaitanya	Dayal Bagh, Agra	27
102	Ajeet	Delhi	26
103	Rahul	Gurgaon	24
104	Shubham	Chennai	25

2. Record or Tuple

Each row of a table is known as record. It is also known as tuple. For example, the following row is a record that we have taken from the above table.

102

Ajeet

Delhi

26

3. Field or Column name or Attribute

The above table “STUDENT” has four fields (or attributes): Student_Id, Student_Name, Student_Addr & Student_Age.

4. Domain

A domain is a set of permitted values for an attribute in table. For example, a domain of month-of-year can accept January, February,…December as values, a domain of dates can accept all possible valid dates etc. We specify domain of attribute while creating a table.

An attribute cannot accept values that are outside of their domains. For example, In the above table “STUDENT”, the Student_Id field has integer domain so that field cannot accept values that are not integers for example, Student_Id cannot has values like, “First”, 10.11 etc.

5. Instance and Schema

I have already covered instance and schema in a separate guide, you can refer the guide here.

6. Keys

This is our next topic, I have covered the keys in detail in separate tutorials. You can refer the keys index here

Difference between RDBMS and DBMS

DBMS	RDBMS
DBMS stores data as file.	RDBMS stores data in tabular form.
Data elements need to access individually.	Multiple data elements can be accessed at the same time.
No relationship between data.	Data is stored in the form of tables which are related to each other.
Normalization is not present.	Normalization is present.
DBMS does not support distributed database.	RDBMS supports distributed database.
It stores data in either a navigational or hierarchical form.	It uses a tabular structure where the headers are the column names, and the rows contain corresponding values.
It deals with small quantity of data.	It deals with large amount of data.
Data redundancy is common in this model.	Keys and indexes do not allow Data redundancy.
It is used for small organization and deal with small data.	It is used to handle large amount of data.
It supports single user.	It supports multiple users.
Data fetching is slower for the large amount of data.	Data fetching is fast because of relational approach.
The data in a DBMS is subject to low security levels with regards to data manipulation.	There exists multiple levels of data security in a RDBMS.
Low software and hardware necessities.	Higher software and hardware necessities.
Examples: XML, Microsoft Access, etc.	Examples: MySQL, PostgreSQL, SQL Server, Oracle, etc.