1
Data
The word data is derived from the Latin which means ‘to give’; data is real given
facts, from which additional facts can be inferred. Data is a collection of known facts
that can be recorded and that have implicit meanings.
2
Database
Database is a collection of related data or operational data extracted from any firm or
organization. In other words, a collection of organized data is called database.
3
DBMS (Database Management System)
DBMS is a collection of programs that enables users to create, maintain, and
manipulate a database. The DBMS is a general purpose software system that
facilitates the process of defining, constructing, and manipulating database.
4
Database Systems
A database system comprises a database of operational data, together with the
processing functionality required to access and manage that data. The combination
of the DBMS and the database is called database systems.
5
Database Catalog
A database catalog contains complete description of the databases, database
objects, database structure, details of users, and constraints etc. that are stored.
6
Program-data independence
In traditional file processing, the structure of the data files is ‘hard-coded” into the
programs. To change the structure of the data file, one or more programs that
access that file, should be changed. The process of changing can introduce errors.
In contrast to this more traditional approach, DBMS access stores the structure in a
catalog, separating the DBMS programs and the data definition. Storing the data and
programs separately is known as program-data independence.
7
User View
The way in which the database appears to a particular user is called user view.
8
DBA (Database Administrator)
DBA is a person who is responsible for authorizing access to the database,
coordinating and monitoring its use, and acquiring software and hardware resources
as needed.
9
End User
End users are the people who want to access the database for different purposes
like, querying, updating, and generating reports.
10
Canned Transactions
Standardized queries and updates on the database using carefully programmed and
tested programs.
11
Deductive Database System
A deductive database system is a database system that supports the proof-theoretic
view of a database, and ,in particular, is capable of deducing are inferring additional
facts from the given facts in the extensional database by applying specified
deductive anxious are rules of inference to those given facts.
12
Persistent object
Object-Oriented database systems are compatible with programming languages
such as c++ and JAVA. An object that is stored in such a way that it survives that
termination of the DBMS program is persistent.
13
Meta Data
Information about the data is called Meta data. The information stored in the catalog
is called Meta data. The schema of a table is an example of Meta data.
14
Transaction processing application
A transaction is a logical unit of database. The processing includes one or more
database operations like, insertion, deletion, modification and retrieval. The database
operations that form a transaction can either be embedded within an application
program on they can be specified interactively via a high-level query language such
as SQL.
The four types of actions involve the database are as follows:
• Database Administration
• Database Designing
• Database Usage by end users.
• System Analysis and Application Programming
Characteristics of Database:
Self – Describing nature of a database system:
A fundamental characteristic of the database approach is that the database system
contains not only the database itself but also complete definitions are description of
the database. Structure and constraints.
• The information stored in the catalogs is called meta – data, and if describes the
structure of the primary database.
• In traditional file processing, data definition is typically part of the application
programs themselves.
Those programs are constrained to work with only one specific database; whose
structure is declared in the application programs.
Responsibilities of DBA:
DBA stands for Data Base Administrator. The purpose of a database administrator is
highly technical, who is responsible for managing the database used in the
organization.
• The database administrator has the responsibility to build the physical design of the
database.
• The database administrator deals with the technical responsibilities like,
o Defence enforcement
o Performance of the database
o Provide access to the database
o Acquire resources such hardware and software components
o Backup of the data from the database
o Recovery of the lost data from the database
o Monitoring and Coordinating the use of database
o Monitoring response time and security breaches.
The end users perform various database operations like querying, updating, and
generating reports.
The different types of end users are as follows:
• Casual end users
• Naive or parametric end users
• Sophisticated end users
• Standalone Users
Some of the capabilities of database management system (DBMS) are as follows:
• Controlling redundancy
• Restricting unauthorized access
• Providing persistent storage for program objects
• Providing storage structures and search techniques for efficient query processing
• Providing backup and recovery
• Providing multiple user interfaces
• Representing complex relationships among data
• Enforcing integrity constraints
Database Approach:– A databases is more than a file it contains information about
more then one entity and information about relationships among the entities.
Information retrieval systems:– It information retrieval system data are stored in file is
a very old rout often used approach to system developed.
Information Queries:–
a) Retrieve the transcript – a list of all courses and grades – of ‘smith’
b) List the name of students who took the section of the ‘Database’ course offered in
fall 2005 and their grades in that section.
c) List the pre-requisites of the “Database” course
Storing the same facts or data at multiple places in the database is considered as
redundancy. In other words, duplication of data is known as redundancy.
Some of the problems with redundant data are as follows:
• Inconsistency of data
• Wastage of memory space
6.15 - Show the result of each of the sample queries in Section 6.5 as it would apply to the
database state in Figure 3.6.
Answer: (QUERY 1) Find the name and address of all employees who work for the 'Research'
department.
Result: FNAME LNAME ADDRESS John Smith 731 Fondren, Houston, TX Franklin Wong 638 Voss,
Houston, TX Ramesh Narayan 975 Fire Oak, Humble, TX Joyce English 5631 Rice, Houston, TX
(QUERY 2) For every project located in 'Stafford', list the project number, the controlling
department number, and the department manager's last name, address, and birth date.
Result: PNUMBER DNUM LNAME ADDRESS BDATE 10 4 Wallace 291 Berry, Bellaire, TX 20-JUN-31 30
4 Wallace 291 Berry, Bellaire, TX 20-JUN-31
(QUERY 3) Find the names of all employees who work on all the projects controlled by
department number 5.
Result: (empty because no tuples satisfy the result). LNAME FNAME
(QUERY 4) Make a list of project numbers for projects that involve an employee whose last
name is 'Smith' as a worker or as a manager of the department that controls the project.
Result: PNO 1 2