A database is an organized collection of data that models aspects of reality. Database management systems (DBMS) allow users and applications to define, create, query, update, and administer databases. Well-known DBMS include MySQL, PostgreSQL, Microsoft SQL Server, Oracle, SAP, and IBM DB2. A DBMS includes components for data definition (DDL), data manipulation (DML), optimization and execution, data security and integrity, data recovery and concurrency, and a data dictionary. The DBMS architecture has three levels - an external level for users, a conceptual level representing the database contents, and an internal level for low-level storage.

1. Submitted by: Ashish Thakur
B.Sc (hons.) bioinformatics
Jaipur National University

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Database
Database management system
DBMS features
DBMS architecture
Overview

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 A database is an organized collection of data. The
data is typically organized to model aspects of reality
in a way that supports processes requiring
information.
Database

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 Database management systems are computer
software applications that interact with the user,
other applications, and the database itself to capture
and analyze data. A general-purpose DBMS is
designed to allow the definition, creation, querying,
update, and administration of databases.
DBMS

5. 
 Well-known DBMSs include MySQL, PostgreSQL,
Microsoft SQL Server, Oracle, SAP and IBM DB2
Examples

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 The DBMS must be able to accept data definition
(external schema, conceptual schema, the internal
schema and all associate mappings) in source form
and convert them into appropriate object form.
 In other words, the DBMS must include DDL
processor or DDL compiler.
Data definition (DDL)

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 The DBMS must be able to handle requests to
retrieve, update or delete existing data in the
database or add new data to the database.
Data manipulation (DML)

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 DML requests must be processed by the optimizer,
component whose purpose is to determining an
efficient of implementing the request.
 The optimizer requests are then executed under the
control of the run-time manager.
Optimization and Execution

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 DBMS must monitor user request and reject any
attempt to violate the security and integrity constant
defined by the DBA.
Data security and Integrity

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 The DBMS must enforce certain recovery and
concurrency controls. DBMS software components
which handles these is basically known as transition
manager or TPC Transaction Processing monitor.
 Backup and Restore
Data Recovery and
Concurrency

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 The data dictionary can be regarded as a database in
its own right (but a system database rather than a
user database).
 It contains “DATA ABOUT THE DATA” (sometimes
called as metadata or descriptors).
Data Dictionary

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Internal level
Conceptual level
External level
DBMS Architecture

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The External level
 How data is viewed by
an individual user.
 Data definition
language declares
objects.
 Data manipulation
language manipulates
database objects e.g.
retrievals and updates.
DDL
DML

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 A representation of the entire information content of
the database.
 The conceptual schema is a definition of the view of
the total database content.
 One can add : security and integrity checks, sematic
models and data dictionary.
The Conceptual level

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 The internal level is a low-level representation of the
entire database.
 Internal record or stored record is built upon
physical records or pages and blocks.
The Internal level

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References

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