abase 1. What is a Database Management System?
Database Management System is a collection of interrelated data and a set of programs to access those data. This is a collection of related data with an implicit meaning and hence is a database. The collection of data, usually referred to as the database, contains information relevant to an enterprise. The primary goal of a DBMS is to provide a way to store and retrieve database information that is both convenient and efficient.
Database systems are designed to manage large bodies of information. Management of data involves both defining structures for storage of information and providing mechanisms for the manipulation of information. In addition, the database system must ensure the safety of the information stored, despite system crashes or attempts at unauthorized access. If data are to be shared among several users, the system must avoid possible anomalous results.
2. What are the kinds/ types of DBMS?
There are four main types of database management systems (DBMS) and these are based upon their management of database structures.
a. Hierarchical DBMS is a data model in which the data is organized into a tree-like structure. The structure allows representing information using parent/child relationships: each parent can have many children, but each child has only one parent (also known as a 1-to-many relationship). All attributes of a specific record are listed under an entity type.
In a database an entity type is the equivalent of a table. Each individual record is represented as a row, and each attribute as a column. Entity types are related to each other using 1: N mappings, also known as one-to-many relationships. This model is recognized as the first database model created by IBM in the 1960s.
Currently the most widely used hierarchical databases are IMS developed by IBM and Windows Registry by Microsoft.
b. Network DBMS when the relationships among data in the database are of type many-to-many. The relationships among many-to-many appear in the form of a network. Thus the structure of a network database is extremely complicated because of these many-to-many relationships in which one record can be used as a key of the entire database.
A network database is structured in the form of a graph that is also a data structure. Though the structure of such a DBMS is highly complicated however it has two basic elements i.e. records and sets to designate many-to-many relationships. Mainly high-level languages such as Pascal, COBOL and FORTRAN etc. were used to implement the records and set structures.
Some well-known database systems that use the network model include: * Integrated Data Store (IDS)
* IDMS (Integrated Database Management System)
* RDM Embedded
* RDM Server
* Univac DMS-1100
c. Relational DBMS is when the database relationships are treated in the form of a table. There are three keys on relational DBMS 1) relation 2) domain 3) attributes. A network means it contains a fundamental constructs sets or records. Sets contains one to many relationship, records contains fields statically table that is composed of rows and columns is used to organize the database and its structure and is actually a two dimension array in the computer memory.
The purpose of the relational model is to provide a declarative method for specifying data and queries: users directly state what information the database contains and what information they want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for answering queries.
A number of RDBMSs are available; some popular examples are Oracle, Sybase, Ingress, Informix, Microsoft SQL Server, and Microsoft Access.
d. Object-Oriented DBMS is a database management system in which information is represented in the form of objects as...
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