DBMS Tutorial Summary
Database Management System (DBMS) is a collection of programs which enables its users to access a database, manipulate data and reporting/representation of data. This is a complete Database Management System tutorial for beginners.
These online Database Management System notes cover basics to advance topics like DBMS architecture, data model, ER model diagram, relational calculus and algebra, concurrency control, keys, data independence, etc. to easily understand and learn DBMS for beginners. Let us start this DBMS tutorial by understanding,
What is DBMS?
Database Management System (DBMS) is software for storing and retrieving users’ data while considering appropriate security measures. It consists of a group of programs that manipulate the database. The DBMS accepts the request for data from an application and instructs the operating system to provide the specific data. In large systems, a DBMS helps users and other third-party software store and retrieve data.
DBMS allows users to create their own databases as per their requirements. The term “DBMS” includes the user of the database and other application programs. It provides an interface between the data and the software application.
What is Database Architecture?
A Database Architecture is a representation of DBMS design. It helps to design, develop, implement, and maintain the database management system. A DBMS architecture allows dividing the database system into individual components that can be independently modified, changed, replaced, and altered. It also helps to understand the components of a database.
A Database stores critical information and helps access data quickly and securely. Therefore, selecting the correct Architecture of DBMS helps in easy and efficient data management.
DBMS Schemas: Internal, Conceptual, External
Database systems comprise of complex data structures. Thus, to make the system efficient for retrieval of data and reduce the complexity of the users, developers use the method of Data Abstraction.
There are mainly three levels of data abstraction:
Internal Level: Actual PHYSICAL storage structure and access paths.
Conceptual or Logical Level: Structure and constraints for the entire database
External or View level: Describes various user views
What is Relational Model?
Relational Model (RM) represents the database as a collection of relations. A relation is nothing but a table of values. Every row in the table represents a collection of related data values. These rows in the table denote a real-world entity or relationship.
The table name and column names are helpful to interpret the meaning of values in each row. The data are represented as a set of relations. In the relational model, data are stored as tables. However, the physical storage of the data is independent of the way the data are logically organized.
Some popular Relational Database management systems are:
DB2 and Informix Dynamic Server – IBM
Oracle and RDB – Oracle
SQL Server and Access – Microsoft