HELLOW Defining DBMS A database management system DBMS
HELLOW…
Defining DBMS A database management system (DBMS) can be an extremely complex set of software programs that controls the organisation, storage and retrieval of data (fields, records and files) in a database. It also controls the security and integrity of the database.
Advantages of DBMS �Using a DBMS to store and manage data comes with advantages, but also overhead. �One of the biggest advantages of using a DBMS is that it lets end users and application programmers access and use the same data while managing data integrity. �Data is better protected and maintained when it can be shared using a DBMS instead of creating new iterations of the same data stored in new files for every new application. �The DBMS provides a central store of data that can be accessed by multiple users in a controlled manner
Three-Schema Architecture
INTERNAL LEVEL �It is the lowest level of data abstraction that deals with physical representation of the database on the computer and is known as physical level. �It describes how the data is physically stored and organized onto the storage medium. �These aspects include storage space allocation techniques for data and indexes.
CONCEPTUAL LEVEL �This level of abstraction deals with logical structure of entire database and thus is known as logical level. �It hides the complexity of physical storage structure. �The conceptual view is the overview of the database and it includes all the information that is going to be represented.
EXTERNAL LEVEL �It is the highest level of abstraction that deals with the users view of the database and thus, is also known as view level. �The external level describes a part of the database for a particular group of users.
CHARACTERISTICS OF DATABASE SELF DESCRIBING APPROACH �A complete definition or description of the database structure and constraints �DBMS software works equally well with any number of database applications �DBMS catalog stores the description of the database. The description is called meta-data
INSULATION BETWEEN PROGRAMS AND DATA. �Program-data independence Allows changing data storage structures and operations without having to change the DBMS access programs �Program - operation independence : The interface (or signature) of an operation includes the operation name and the data types of its arguments (or parameters). �The implementation (or method) of the operation is specified separately and can be changed without affecting the interface. Data Abstraction. �A data model is used to hide storage details and present the users with a conceptual view of the database
SUPPORT OF MULTIPLE VIEWS OF DATA �A database typically has many users, each of whom may require a different perspective or view of the database. �A view may be a subset of the database or it may contain virtual data that is derived from thedatabase files but is not explicitly stored. �A multiuser DBMS whose users have a variety of applications must provide facilities for defining multiple views
SHARING OF DATA AND MULTIUSER. �Allow multiple users to access the database at the same time �Concurrency control Allowing a set of concurrent users to retrieve and to update the database. �Concurrency control within the DBMS guarantees that each transaction is correctly executed or completely aborted. �OLTP (Online Transaction Processing) is a major part of database applications
DATA BASE MALL
MEENAKSHI MALL
ENTITIES �Entertainment �Food Court �Shopping �Staff �Parking
Entertainment
Food Court
Shopping
STAFF
Parking
Summary �In this, we define a data base as collection of related data. �Typical database represents some aspects of the real world. �A DBMS is a generalized software package for implementing and maintaining a computerized database. �Database and software together form a database system. �In this, we represent a list of capabilities that should be provided by the DBMS software to the DBA.
Arshia Saniya Tasmiya
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