what is database management system




A database-management system (DBMS) is a collection of interrelated data and a set of programs to access those data. 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.

Because information is so important in most organizations, computer scientists have developed a large body of concepts and techniques for managing data.



Frequently Asked Questions

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Ans: The specialization relationship may also be referred to as a superclass-subclass relationship. Higher- and lower-level entity sets also may be designated by the terms superclass and subclass, respectively. The person entity set is the superclass of the employee and student subclasses. view more..
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Ans: A database system is a collection of interrelated data and a set of programs that allow users to access and modify these data. A major purpose of a database system is to provide users with an abstract view of the data. That is, the system hides certain details of how the data are stored and maintained. view more..
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Ans: Self-describing nature of a database system Insulation between programs and data, and data abstraction Support of multiple views of the data Sharing of data and multiuser transaction processing view more..
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Ans: A database-management system (DBMS) is a collection of interrelated data and a set of programs to access those data. view more..
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Ans: Databases are widely used in enterprises, banking and finance, universities, airlines, telecommunication, etc. view more..
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Ans: Specialization is the process of defining a set of subclasses of an entity type; this entity type is called the superclass of the specialization. We use the term generalization to refer to the process of defining a generalized entity type from the given entity types. view more..
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Ans: we discuss differences between specialization/generalization lattices (multiple inheritance) and hierarchies (single inheritance), and elaborate on the differences between the specialization and generalization processes during conceptual database schema design. We discuss constraints that apply to a single specialization or a single generalization. view more..
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Ans: it is sometimes necessary to represent a single superclass/subclass relationship with more than one superclass, where the superclasses represent different entity types. In this case, the subclass will represent a collection of objects that is a subset of the UNION of distinct entity types. view more..
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Ans: For our sample database application, consider a UNIVERSITY database that keeps track of students and their majors, transcripts, and registration as well as of the university’s course offerings. The database also keeps track of the sponsored research projects of faculty and graduate students. view more..
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Ans: The basic notation for specialization/generalization is to connect the subclasses by vertical lines to a horizontal line, which has a triangle connecting the horizontal line through another vertical line to the superclass. A blank triangle indicates a specialization/generalization with the disjoint constraint, and a filled triangle indicates an overlapping constraint. view more..
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Ans: The similarities and differences between conceptual modeling and knowledge representation, and introduces some of the alternative terminology and a few additional concepts.The goal of KR techniques is to develop concepts for accurately modeling some domain of knowledge by creating an ontology that describes the concepts of the domain and how these concepts are interrelated. view more..
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Ans: Recovery from transaction failures usually means that the database is restored to the most recent consistent state just before the time of failure. To do this, the system must keep information about the changes that were applied to data items by the various transactions. view more..
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Ans: Several types of locks are used in concurrency control. To introduce locking concepts gradually, first we discuss binary locks, which are simple, but are also too restrictive for database concurrency control purposes, and so are not used in practice. Then shared/exclusive locks - also known as read/write locks - which provide more general locking capabilities and are used in practical database locking systems. view more..
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Ans: In this section we discuss the concepts of concurrent execution of transactions and recovery from transaction failures. view more..
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Ans: Conceptual modeling is a very important phase in designing a successful database application. Generally, the term database application refers to a particular database and the associated programs that implement the database queries and updates. view more..
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Ans: Data is converted into information, and information is then evaluated and organised so that it can be used purposefully as knowledge. view more..
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Ans: A database system is a collection of interrelated data and a set of programs that allow users to access and modify these data. A major purpose of a database system is to provide users with an abstract view of the data. That is, the system hides certain details of how the data are stored and maintained. view more..
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Ans: In this section we discuss the concepts of concurrent execution of transactions and recovery from transaction failures view more..




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