RDBMS and DBMS - Concepts and Basics

DBMS

Database management system is a collection of programs that enables user to store, retrieve, update and delete information from a database.

RDBMS

Relational Database Management system (RDBMS) is a database management system (DBMS) that is based on the relational model. Beauty about relational database is that the data stored in them can be retrieved or reorganized in different ways without making changes to the database tables. Data from relational database can be accessed using a API, Structured Query Language (SQL).

SQL

Structured Query Language(SQL) is a language designed specifically for communicating with databases. SQL is an ANSI (American National Standards Institute) standard.

Advantages of SQL

• SQL is not a proprietary language used by specific database vendors. Almost every major DBMS supports SQL, so learning this one language will enable programmers to interact with any database like ORACLE, SQL Server, MySQL, DB2, Postgresql etc.

• Learning SQL is very easy. We can make SQL statements using a predefined set of English words. Since there aren't many SQL keywords, it is very easy to remember them.

• Very complex and precision oriented database operations can be performed using SQL statements. 

Database Definition

A DATABASE is a collection of logically related tables which are stored in a file or set of files. A database is a structured object that consists of data and metadata (Table definitions).

Table Name : Employee

Employee_ID	Employee_Name
1	John
2	Alex
3	James
4	Roy
5	Kay

Database Field

A database field can be described as a part of a record which is reserved for a specific type of data. Example of a database field are Employee Name, Employee Salary etc.

Fields are defined by:

• Field name (ex. Employee_ID)
• Data type (ex. Int, Long, Double, Varchar, Blob )
• Field size ( ex. Varchar (100) )

Database Record

A record is the collection of fields where each field contains specific information: i.e. an Employee Name, Salary etc.

Database Table

A database table is a collection of records of a specific type. For example, employee table, salary table etc.