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1.Introduction to Databases and DBMS
2.Bibliography - Text Books
T.Connolly, Database Systems - A Practical Approach to Design, Implementation and Management, 2nd Edition, Addison-Wesley, 1998
Paolo Atenzi, Database Systems - Concepts, languages and Architectures, McGraw Hill1999
F. D. Rolland The Essence of Databases - Prentice Hall 1998
C.J. Date, An Introduction to Database Systems - Volume 1, 6th edition, Addison-Wesley, 1995.
R. Elmasri & S.B. Navathe, Fundamentals of Database Systems, 2nd edition, Addison-Wesley, 1994.
T J Teorey - Database Modelling and Design, 2nd Edition, Morgan Kaufmann 1994
F van der Lans - SQL Guide to Oracle , 2nd Edition, Addison Wesley1994
T.Connolly, Database Systems - A Practical Approach to Design, Implementation and Management, 2nd Edition, Addison-Wesley, 1998
Paolo Atenzi, Database Systems - Concepts, languages and Architectures, McGraw Hill1999
F. D. Rolland The Essence of Databases - Prentice Hall 1998
C.J. Date, An Introduction to Database Systems - Volume 1, 6th edition, Addison-Wesley, 1995.
R. Elmasri & S.B. Navathe, Fundamentals of Database Systems, 2nd edition, Addison-Wesley, 1994.
T J Teorey - Database Modelling and Design, 2nd Edition, Morgan Kaufmann 1994
F van der Lans - SQL Guide to Oracle , 2nd Edition, Addison Wesley1994
3.Databases and Information Systems
An Information system is a model about some phenomena in the world - the Universe of Discourse - (e.g. an organisation)
retrieves, updates and deletes these facts
derives other facts from existing ones
Data - raw facts/details of the model
DATABASE- A shared collection of logically related data (and a description of this data), designed to meet the organisation needs of an organisation
The Database Management System (DBMS) - software that enables usersto define, create and maintain the database and provides controlled access to the database
An Information system is a model about some phenomena in the world - the Universe of Discourse - (e.g. an organisation)
retrieves, updates and deletes these facts
derives other facts from existing ones
Data - raw facts/details of the model
DATABASE- A shared collection of logically related data (and a description of this data), designed to meet the organisation needs of an organisation
The Database Management System (DBMS) - software that enables usersto define, create and maintain the database and provides controlled access to the database
4.Changes in the UoD are reflected in the Database
5.A Sample Database
6.An Abstract Architecture of Information Systems
7.Requirements of a Database System
8.Traditional Approach Applications developed in an ad-hoc and opportunistic manner
Data requirements for applications derived independently
Data files developed for individual applications
Application programs are data dependent
Data requirements for applications derived independently
Data files developed for individual applications
Application programs are data dependent
9.Files Dedicated to Application Programs
10.Database Approach
Centralisation of information manageent
Data shared by different groups of users and application programs
Provision of multiple interfaces
Representation of complex relationships between data
Integrity constraint handling
Advanced facilities for backup and recovery
Centralisation of information manageent
Data shared by different groups of users and application programs
Provision of multiple interfaces
Representation of complex relationships between data
Integrity constraint handling
Advanced facilities for backup and recovery
11.Data Sharing in a Database Environment
12.Advantages
13.Disadvantages
size
complexity
cost
Additional hardware costs
Higher impact of failure
Recovery more difficult
size
complexity
cost
Additional hardware costs
Higher impact of failure
Recovery more difficult
14.Functions of a DBMS
Data storage, retrieval, update
A user-accessible catalog
Transaction support
Concurrency control
Recovery services
Authorisation services
Support for data communication
Integrity services
Data independence
Utility services
Data storage, retrieval, update
A user-accessible catalog
Transaction support
Concurrency control
Recovery services
Authorisation services
Support for data communication
Integrity services
Data independence
Utility services
15.Interacting with a Database
16.Interaction of DBMS with Operating System
17.Data Models, Schemas and Instances
18.Developing a Database System
19.Maintaining a Database System - the Task of the DBA
Maintaining information structure of the database (metadata in the Data Dictionary)
Define user requirements of data usage
Monitor use of database
Determine and optimise storage structure and access strategies
Define authorisation checks
Define strategies for backup and recovery
Define testing procedures and changeover policy
Maintaining information structure of the database (metadata in the Data Dictionary)
Define user requirements of data usage
Monitor use of database
Determine and optimise storage structure and access strategies
Define authorisation checks
Define strategies for backup and recovery
Define testing procedures and changeover policy
20.The ANSI/SPARC 3-levels Architecture
21.Languages in a Database Environment
22.Data Definition - Functionality of DDL
Functionality is dependent on particular language
Basic functions include:
creation of data structure supported by data model e.g. CREATE TABLE for the relational model
modification of data structure e.g. ALTER TABLE
deletion of data structure e.g. DROP TABLE
creation of indexes on particular data items for data access e.g. CREATE INDEX
Functionality is dependent on particular language
Basic functions include:
creation of data structure supported by data model e.g. CREATE TABLE for the relational model
modification of data structure e.g. ALTER TABLE
deletion of data structure e.g. DROP TABLE
creation of indexes on particular data items for data access e.g. CREATE INDEX
23.Data Manipulation - Functionality of DML
Functionality is dependent on particular language
Basic functions include:
retrieval of data e.g. SELECT operator for the relational model
modification of data e.g. UPDATE operator
deletion of data e.g. DELETE operator
creation of new data e.g. INSERT operator
Most DML's have built in functions e.g. SUM, COUNT, AVG etc
Functionality is dependent on particular language
Basic functions include:
retrieval of data e.g. SELECT operator for the relational model
modification of data e.g. UPDATE operator
deletion of data e.g. DELETE operator
creation of new data e.g. INSERT operator
Most DML's have built in functions e.g. SUM, COUNT, AVG etc
24.The System Catalog (Data Dictionary)
A system catalog contains the description of the database
Often referred to as the 'data dictionary'
For the relational data model the catalog is defined and interrogated using the same languages that can be used at the application level (i.e. DDL and DML) - but includes extra commands
The catalog describes:
the basic make up of the data items
base data
views
authorisation data
some integrity constraints
A system catalog contains the description of the database
Often referred to as the 'data dictionary'
For the relational data model the catalog is defined and interrogated using the same languages that can be used at the application level (i.e. DDL and DML) - but includes extra commands
The catalog describes:
the basic make up of the data items
base data
views
authorisation data
some integrity constraints
25.A view represents virtual data structures which are derived from base data structures
Views permit users to perceive the database in terms of derived data which correspond exactly to their applications
Views insulate programmers from base data and enable changes to definitions of base data without affecting aplication programs
Views permit users to perceive the database in terms of derived data which correspond exactly to their applications
Views insulate programmers from base data and enable changes to definitions of base data without affecting aplication programs
26.Embedded Sublanguages
Statements of an embedded sublanguage appear within a host language
Usually the same language which is used in an interpretive mode (as a query language) is also used as an embedded sublanguage e.g. SQL
Host language 'programming is required to overcome limitations of query language e.g. recursion and enforcement of integrity constraints
Embedded language statements can correspond to data definitions including definition of views (DDL) and data manipulation (DML)
Embedded language are handled by a preprocessor
Mismatch problems in relational DBMS - set oriented SQL versus record oriented host languages
Statements of an embedded sublanguage appear within a host language
Usually the same language which is used in an interpretive mode (as a query language) is also used as an embedded sublanguage e.g. SQL
Host language 'programming is required to overcome limitations of query language e.g. recursion and enforcement of integrity constraints
Embedded language statements can correspond to data definitions including definition of views (DDL) and data manipulation (DML)
Embedded language are handled by a preprocessor
Mismatch problems in relational DBMS - set oriented SQL versus record oriented host languages
27.A General Database System Architecture
28.Database Manager software components
Authorization control - check authorised to carry out operation
Command processor - control of operation
Integrity checker - updates checked against constraints
Query Optimiser - determine optimal strategy for query
Transaction Manager - controls transaction operations
Scheduler - ensure concurrent operations do not conflict
Recovery Manager - if failure returns to a consistent state
Buffer Manger - transfer of data between memeory and CPU
RM and BM often referred to collectively as Data manager
Authorization control - check authorised to carry out operation
Command processor - control of operation
Integrity checker - updates checked against constraints
Query Optimiser - determine optimal strategy for query
Transaction Manager - controls transaction operations
Scheduler - ensure concurrent operations do not conflict
Recovery Manager - if failure returns to a consistent state
Buffer Manger - transfer of data between memeory and CPU
RM and BM often referred to collectively as Data manager
29.Integrated Environment
Integrated software built around the RDBMS eg ORACLE Developer 2000
SQL*Forms
SQL*Report
PL/SQL
Integrated software built around the RDBMS eg ORACLE Developer 2000
SQL*Forms
SQL*Report
PL/SQL
30.Classification of DBMS
31.Requirements for Database Consistency
Recovery
System failures, either of hardware or software, must not result in an inconsistent database.
A transaction must execute in its entirety or not at all.
Concurrency Control
The simultaneous execution of many different application programs must be such that each transaction does not interfere with another transaction.
The concurrent execution of transactions must be such that each transaction appears to execute in isolation.
Recovery
System failures, either of hardware or software, must not result in an inconsistent database.
A transaction must execute in its entirety or not at all.
Concurrency Control
The simultaneous execution of many different application programs must be such that each transaction does not interfere with another transaction.
The concurrent execution of transactions must be such that each transaction appears to execute in isolation.
32.Conclusions
A database is a central component of any contemporary information system
The operations on the database and the mainenance of database consistency is handled by a DBMS
There exist stand alone query languages or embedded languages but both deal with definition (DDL) and manipulation (DML) aspects
The structural properties, constraints and operations permitted within a DBMS are defined by a data model - hierarchical, network, relational
Recovery and concurrency control are essential
A database is a central component of any contemporary information system
The operations on the database and the mainenance of database consistency is handled by a DBMS
There exist stand alone query languages or embedded languages but both deal with definition (DDL) and manipulation (DML) aspects
The structural properties, constraints and operations permitted within a DBMS are defined by a data model - hierarchical, network, relational
Recovery and concurrency control are essential
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