Question

Briefly describe the function of the DBMS in a database system.

Answer 1

A database system is basically a record keeping system. It is defined as a collection of interrelated data stored together to serve multiple applications. Where the datas are stored in a common and controlled manner so they are interpreted of programs that use the data. A database management system (DBMS) is a collection of programs that enables uses to create and maintain a data base. hence it is a general purpose software system that facilitate the process of construction, defining and manipulating database for various applications.

There are several functions that a DBMS performs to ensure data integrity and consistency of data in the database.

• Data Dictionary Management: Data Dictionary is where the DBMS stores definitions of the data elements and their relationships (metadata). which descriptions of data items are stored and which is accessible to users. This function removes structural and data dependency and provides the user with data abstraction. In turn, this makes things a lot easier on the end user. The Data Dictionary is often hidden from the user and is used by Database Administrators and Programmers.
• Data Storage Management: This particular function is used for the storage of data and any related data entry forms or screen definitions, report definitions, data validation rules, procedural code, and structures that can handle video and picture formats. Users do not need to know how data is stored or manipulated. Also involved with this structure is a term called performance tuning that relates to a database’s efficiency in relation to storage and access speed.
• Data Transformation and Presentation: Using the data transformation and presentation function database can determine the difference between logical and physical data formats. This function exists to transform any data entered into required data structures.
• Security Management: Database security refers to protection of data against unauthorised person or unauthorised modification on description.This is one of the most important functions in the DBMS. Security management sets rules that determine specific users that are allowed to access the database. Users are given a username and password or sometimes through biometric authentication.
• Multiuser Access Control: Multiuser access control is a very useful tool in a DBMS, individual pieces of data shared among several different users or different purpose.
• Backup and Recovery Management: The DBMS provides mechanisms for backing up data periodically and recovering from different types of failures. This prevents the loss of data
• Data Integrity Management: It means unification of several distinct data files with any redundancy ( data redundancy means duplication of data ) among the those files partially or whole eliminated.
• Database Access Languages: A data base system provides two different types of languages one to specify the database schema ( design of database eg: table to store) it uses DDL(Data Definition Language) and the other to express database queries and updates it uses DML ( Data Manipulation Language).
• Database Communication Interfaces: This refers to how a DBMS can accept different end user requests through different network environments. An example of this can be easily related to the internet. A DBMS can provide access to the database using the Internet through Web Browsers (Internet Explorer, Netscape, google chrome).
• Transaction Management: This refers to how a DBMS must supply a method that will guarantee that all the updates in a given transaction are made or not made.All transactions must follow what is called the ACID properties.

Atomicity: This property states that a transaction must be treated as an atomic unit, that is, either all of its operations are executed or none. There must be no state in a database where a transaction is left partially completed. States should be defined either before the execution of the transaction or after the execution/abortion/failure of the transaction.

Consistency: The database must remain in a consistent state after any transaction. No transaction should have any adverse effect on the data residing in the database. If the database was in a consistent state before the execution of a transaction, it must remain consistent after the execution of the transaction as well.

Durability: The database should be durable enough to hold all its latest updates even if the system fails or restarts. If a transaction updates a chunk of data in a database and commits, then the database will hold the modified data. If a transaction commits but the system fails before the data could be written on to the disk, then that data will be updated once the system springs back into action.

Isolation: In a database system where more than one transaction are being executed simultaneously and in parallel, the property of isolation states that all the transactions will be carried out and executed as if it is the only transaction in the system. No transaction will affect the existence of any other transaction.