DATABASEDATABASE ENVIRONMENTWHY STUDY DATABASEDBMS & ITS FUNCTIONSSTRUCTURE OF DBMSDBA

Database:

A very large, integrated collection of data. A Database is a well organized collection of data that are

related in a meaningful way which can be accessed in different logical orders but are stored only once

The record of students maintained by your college is a useful database

Models a real-world enterprise◦ Entities (e.g., teams, games)

A Database Management System (DBMS) is a software system designed to store, manage, and facilitate access to databases. BACK

Stored data base definitoin (META DATA)

Stored Database

Database System DBMS

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DATA BASE SYSTEM ENVIRONMENT

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The database system contains not only the database itself but also a complete definition or description of the database structure and constraint. This definition is stored in the system catalog.

The information stored in the catalog is called metadata that is the “data about the data”

An important property of database system is that the structure of data files is stored in the DBMS catalog separately from the access program.

We call this property as program-data-independence .

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Due to this property we can change the structure of data files in the catalog but no need to change the programs.

The Purpose of the database system is to provide an environment that is both convenient an efficient to use in

Retrieving information from the database Storing information into the database

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Shift from computation to information◦ always true for corporate computing◦ Web made this point for personal computing◦ more and more true for scientific computing

Need for DBMS has exploded in the last years◦ Corporate: “customer relationship mgmt”, “supply chain mgmt”,

“data warehouses”, etc.◦ Scientific: digital libraries, Human Genome project, NASA Mission

to Planet Earth, physical sensors, grid physics network DBMS encompasses much of CS in a practical discipline

◦ OS, languages, theory, AI, multimedia, logic◦ Yet traditional focus on real-world apps

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DBMS is the software that interprets and processes user’s request to retrieve information from a database

DBMS provides security facilities in a variety of forms, both to prevent unauthorized access and to prevent authorized users from accessing data concurrently without any inconsistency in the database

The primary purpose of a DBMS which is basically a collection of programs is to allow a user to store, update, retrieve data.

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Data Definition DBMS must be able to access data

definition in source form and convert them to the appropriate object form. In other words DBMS must include language processor component for each of the various data definition language(DDL).

Data Manipulation DBMS must include a DML processor

component. The DBMS must be able to handle request from the user to see, retrieve, update , delete or add the new record to the database.

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DATA SECURITY AND INTEGRITY

DBMS must monitor user request & reject any attempt to violate the security & integrity rules define by the DBA.

DATA DICTIONARY

The dictionary contains data about the data rather than the raw data.

Data Dictionary contains the information about entities, attributes, mapping etc.

DBMS should perform all the functions as efficiently as possible.

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A typical DBMS has a layered architecture.

The figure does not show the concurrency control and recovery components.

Each database system has its own variations.

Query Optimization

and ExecutionRelational Operators

Files and Access Methods

Buffer Management

Disk Space Management

DB

These layersmust considerconcurrencycontrol andrecovery

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DBMS vendors, programmers◦ Oracle, IBM, MS, Sybase, …

End users in many fields◦ Business, education, science, …

DB application programmers◦ Build enterprise applications on top of DBMSs◦ Build web services that run off DBMSs

Database administrators (DBAs)◦ Design logical/physical schemas◦ Handle security and authorization◦ Data availability, crash recovery ◦ Database tuning as needs evolve

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DBA is the person or the group of persons who is responsible for the management of the database.

The DBA is responsible for defining the database structure, storage structure and the access methods, authorizing access to the database by grant the permission to the user

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