database management system

 INTRODUCTION

                 A DBMS is software that allows creation, definition and manipulation of database, allowing users to store, process and analyse data easily.  DBMS provides us with an interface or a tool, to perform various operations like creating database, storing data in it, updating data, creating tables in the database and a lot more.  DBMS also provides protection and security to the databases.  It also maintains data consistency in case of multiple users. Here are some examples of popular DBMS used these days:  MySql,  Oracle,  SQL Server  IBM DB2 DATABASE. 

 DBMS Applications 

                where we use Database Management Systems are

 Telecom: There is a database to keeps track of the information regarding calls made, network usage, customer details etc

 Industry: Where it is a manufacturing unit, warehouse or distribution centre, each one needs a database to keep the records of ins and outs 

 Banking System: For storing customer info, tracking day to day credit and debit transactions, generating bank statements etc.

  Sales: To store customer information, production information and invoice details.

  Airlines: To travel though airlines, we make early reservations; this reservation information along with flight schedule is stored in database.

  Education sector: Database systems are frequently used in schools and colleges to store and retrieve the data regarding student details, staff details, course details, exam details, payroll data, attendance details, fees details etc 

PURPOSE OF DATABASE SYSTEMS 

                 The main purpose of database systems is to manage the data. Consider a university that keeps the data of students, teachers, courses, books etc. To manage this data we need to store this data somewhere where we can add new data, delete unused data, update outdated data, retrieve data, to perform these operations on data we need a Database management system that allows us to store the data in such a way so that all these operations can be performed on the data efficiently.

A DBMS acts as a middleman between the user and the database. It simplifies the data management process and ensures the data’s security, consistency, and integrity.

 It works in the following way:

1. Organizing Data: The DBMS organizes your database files, categorizing them in a way that makes them easily retrievable. Data organization can be based on various factors such as the data type, relationships between the data, etc.
2. Access Control: The system provides end users more access and control over the data. It ensures appropriate security measures are in place so that only authorized persons can access specific parts of the database.
3. Data Interaction: System users are given facilities to perform various operations on the data, such as creating new data, updating existing data, deleting unnecessary data, and retrieving required data.
4. Concurrency: The DBMS also manages concurrency, which means it allows multiple users to access and modify the data simultaneously without compromising data integrity.
5. Backup and Recovery: Another crucial function of a DBMS is managing backups and recovery. It ensures that the data can be recovered from backups without any discrepancies in case of any failure or data loss.
6. Data Integrity: The DBMS ensures data integrity by enforcing rules on the data. These rules ensure that the data remains consistent and accurate.

 Characteristics of DBMS 

                Data stored into Tables: Data is never directly stored into the database. Data is stored into tables, created inside the database

               Reduced Redundancy: In the modern world hard drives are very cheap, but earlier when hard drives were too expensive, unnecessary repetition of data in database was a big problem. But DBMS follows Normalisation which divides the data in such a way that repetition is minimum. 

                Data Consistency: On Live data, i.e. data that is being continuosly updated and added, maintaining the consistency of data can become a challenge. But DBMS handles it all by itself. 

                 Support Multiple user and Concurrent Access: DBMS allows multiple users to work on it(update, insert, delete data) at the same time and still manages to maintain the data consistency.

                 Query Language: DBMS provides users with a simple Query language, using which data can be easily fetched, inserted, deleted and updated in a database. Advantages of DBMS 

                  Controls database redundancy: It can control data redundancy because it stores all the data in one single database file and that recorded data is placed in the database. 

                 Data sharing: In DBMS, the authorized users of an organization can share the data among multiple users. 

                 Easily Maintenance: It can be easily maintainable due to the centralized nature of the database system.

                Reduce time: It reduces development time and maintenance need. 

                Backup: It provides backup and recovery subsystems which create automatic backup of data from hardware and software failures and restores the data if required. 

               multiple user interface: It provides different types of user interfaces like graphical user interfaces, application program interfaces Disadvantages of DBMS 

               Cost of Hardware and Software: It requires a high speed of data processor and large memory size to run DBMS software. 

              Size: It occupies a large space of disks and large memory to run them efficiently. 

              Complexity: Database system creates additional complexity and requirements. 

               Higher impact of failure: Failure is highly impacted the database because in most of the organization, all the data stored in a single database and if the database is damaged due to electric failure or database corruption then the data may be lost forever. View of Data in DBMS Abstraction is one of the main features of database systems. 

 Hiding irrelevant details from user and providing abstract view of data to users, helps in easy and efficient user-database interaction. 

the three level of DBMS architecture, The top level of that architecture is “view level”. The view level provides the “view of data” to the users and hides the irrelevant DATABASE MANAGEMENT SYSTEMS  details such as data relationship, database schema, constraints, security etc from the user

Database languages

                It is  used to read, update and store data in a database. There are several such languages that can be used for this purpose; one of them is SQL (Structured Query Language). 

 DDL – Data Definition Language: (CREATE,DROP,ALTER,TRUNCATE,COMMENT,RENAME) 

 DML – Data Manipulation Language: (INSERT, UPDATE,DELETE) 

 DCL – Data Control Language: (GRANT,REVOKE) 

TCL-Transaction Control Language: (COMMIT,ROLLBACK)

(Data Manipulation Language) 

               The SQL commands that deals with the manipulation of data present in the database belong to DML or Data Manipulation Language and this includes most of the SQL statements.

 Any access to the stored data is done by the data manager. A user’s request for data is-received by the data manager, which detern1ines the physical record required. The decision as 10 which physical record is needed may require some preliminary consultation of the database and/or the data dictionary prior to the access of the actual data itself. 

The data manager sends the request for a specific physical record to the file manager. The file manager decides which physical block of secondary storage devices contains the required record and sends the request for the appropriate block to the disk manager. A block is a unit of physical input/output operations between primary and secondary storage. 

The disk manager retrieves the block and sends it to the file manager, which sends the required record to the data managerDatabase users are the persons who interact with the database and take the benefits of database. They are differentiated into different types based on the way they expect to interact with the system.

 Naive users: They are the unsophisticated users who interact with the system by using permanent applications that already exist. Example: Online Library Management System, ATMs (Automated Teller Machine), etc.

 Application programmers: They are the computer professionals who interact with system through DML. They write application programs.

 Sophisticated users: They interact with the system by writing SQL queries directly through the query processor without writing application programs.

 Specialized users: They are also sophisticated users who write specialized database applications that do not fit into the traditional data processing framework.

 Example: Expert System, Knowledge Based System, etc.The life cycle of database starts from designing, implementing to administration of it

.A database for any kind of requirement needs to be designed perfectly so that it should work without any issues.
 Once all the design is complete, it needs to be installed. Once this step is complete, users start using the database. The database grows as the data grows in the database.

 When the database becomes huge, its performance comes down. Also accessing the data from the database becomes challenge. There will be unused memory in database, making the memory inevitably huge. These administration and maintenance of database is taken careby database 

Administrator 

              A DBA has many responsibilities. A good performing database is in the hands of DBA. Database Administrators coordinate all the activities of the database system. They have all the permissions 

.A Database Transaction is a logical unit of processing in a DBMS which entails one or more database access operation. In a nutshell, database transactions represent realworld events of any enterprise. 

 All types of database access operation which are held between the beginning and end transaction statements are considered as a single logical transaction in DBMS.

 efficiency, and make better decisions. Thanks for reading!