UNIT
1
INTRODUCTION TO DATABASE
IT 121- FUNDAMENTALS OF DATABASE SYSTEM
-RIZALYN D. NUGUIT, LPT.
WHAT IS DATABASE SYSTEM?
 Database system is a computerized record-keeping system. It is
a computerize system whose overall purpose is to store
information and to allow users to retrieve and update that
information on demand.
 Information is anything that is significant to the individual or
organization concerned.
Data
Data is used to refer to what is
actually stored in the database.
Information
Information is used to refer to
meaning of that data as understood
by some user.
OPERATIONS
 Adding new file to database
 Inserting data into existing files
 Retrieving data from existing files
 Deleting data from existing files
 Changing data in existing files
 Removing existing files from the database
DATABASE
 Database a collection of related data
 Data known facts that can be recorded and that have implicit meaning.(name,
telephone numbers and address)
 Database Management System(DBMS) the software that manages and controls
access to the database
 Database application is simply a program that interacts with the database at some
point in its execution
 Database system to be a collection of application programs that interact with the
database along with the DBMS and database itself
COMMON EXAMPLES OF A DATABASE
 Purchases from the supermarket
 Purchases using your credit card
 Booking a holiday at the travel agents
 Using the local library
 Using the Internet
TRADTIONAL FILE-BASED SYSTEM
File-Based Approach
A collection of application programs that perform services for the system end-users such as the
production of reports. Each program defines and manages its own data
 File-based systems were an early attempt to computerize the manual filing system
 The file based system was developed in response to the needs of industry for more efficient data
access.
 The manual filing system works well while the number of items to be stored is small.
 The manual filing system breaks down when we have to cross-reference or process the information in
the files
FILE PROCESSING SYSTEM
ADVANTAGES OF DATABASE APPROACH
LIMITATIONS OF THE FILE-BASED APPROACH
Data Redundancy
 Since each application has its own data file, the same data may have to be recorded
and stored in many files. For example, personal file and payroll file, both contain data
on employee name, designation etc. The result is unnecessary duplicate or redundant
data items. This redundancy requires additional or higher storage space, costs extra
time and money, and requires additional efforts to keep all files up to-date.
Data Inconsistency
 Data redundancy leads to data inconsistency especially when data is to be updated.
Data inconsistency occurs due to the same data items that appear in more than one
file do not get updated simultaneously in each and every file
LIMITATIONS OF THE FILE-BASED APPROACH
Lack of Data Integration:
 Since independent data file exists, users face difficulty in getting information on any ad
hoc query that requires accessing the data stored in many files. In such a case
complicated programs have to be developed to retrieve data from every file or the
users have to manually collect the required information
Program Dependence:
 The reports produced by the file processing system are program dependent, which
means if any change in the format or structure of data and records in the file is to be
made, the programs have to modified correspondingly. Also, a new program will have
to be developed to produce a new report
LIMITATIONS OF THE FILE-BASED APPROACH
Data Dependence:
 The Applications/programs in file processing system are data dependent i.e., the file
organization, its physical location and retrieval from the storage media are dictated by the
requirements of the particular application. For example, in payroll application, the file may be
organized on employee records sorted on their last name, which implies that accessing of
any employee's record has to be through the last name only.
Poor Data Control:
 There was no centralized control at the data element level, hence a traditional file system is
decentralized in nature. It could be possible that the data field may have multiple names
defined by the different departments of an organization and depending on the file it was in.
This situation leads to different meaning of a data field in different context or same meaning
for different fields. This causes poor data control.
DATABASE APPROACH
WHAT IS DATABASE?
 A database refers to a collection of logically related information organized so that it
can be easily accessible, managed, and updated. Databases are generally accessed
electronically from a computer system and are usually controlled by a database
management system (DBMS). The database administrator (DBA) is the individual
responsible for managing the databases, including database security, access control,
backup, and disaster recovery.
WHAT IS A DATABASE MANAGEMENT SYSTEM?
 A Database Management System (DBMS) is a well-known term in data analysis. It
refers to a collection of programs that enable users to access databases and
manipulate, maintain, report, and relate data. A DBMS is often used to reduce data
redundancy, share data in a controlled way, and reduce data integrity problems. DBMS
is not an information system but is simply software.
WHAT IS A DATABASE MANAGEMENT SYSTEM?
 The relational model, which saves data in table formats, is the most widely used
DBMS. The relational DBMS organizes information into rows, columns, and tables,
making it easier to find relevant information. Relational databases are popular
because they are easy to extend, and new data categories can be added after the
original database is created without large amounts of modification.
 The Structured Query Language (SQL) is considered the standard user and
application program interface for a relational database, and all relational DBMS
software supports SQL. Examples include FileMaker Pro, Microsoft Access, Microsoft
SQL Server, MySQL, and Oracle.
DATABASE VS. DBMS
 Database is a collection of organized, related tables (data stored in rows and
columns)
 Database Management System - Also known as DBMS is Software used to create and
maintain a database.
DATABASE SYSTEM COMPONENTS
Hardware
Software
Procedures
Database Access Language
Data
1. HARDWARE
 Hardware refers to the physical, electronic devices such as computers
and hard disks that offer the interface between computers and realworld systems.
2. SOFTWARE
 Software is a set of programs used to manage and control the database and includes
the database software, operating system, network software used to share the data
with other users, and the applications used to access the data.
3. DATA
 Data are raw facts and information that need to be organized and processed to make
it more meaningful. Database dictionaries are used to centralize, document, control,
and coordinate the use of data within an organization. A database is a repository of
information about a database (also called metadata).
4. PROCEDURES
 Procedures refer to the instructions used in a database management system and
encompass everything from instructions to setup and install, login and logout, manage
the day-to-day operations, take backups of data, and generate reports.
5. DATABASE ACCESS LANGUAGE
 Database Access Language is a language used to write commands to access, update,
and delete data stored in a database. Users can write commands using Database
Access Language before submitting them to the database for execution. Through
utilizing the language, users can create new databases, tables, insert data, and delete
data.
DATABASE DESIGN
ADVANTAGES OF DBMS
Redundancy problem can be solved.
 In the File System, duplicate data is created in many places because all the programs
have their own files which create data redundancy resulting in wastage of memory. In
DBMS, all the files are integrated in a single database. So there is no chance of
duplicate data.
 For example: A student record in a library or examination can contain duplicate
values, but when they are converted into a single database, all the duplicate values are
removed.
Has a very high security level.
 Data security level is high by protecting your precious data from unauthorized access.
Only authorized users should have the grant to access the database with the help of
credentials.
ADVANTAGES OF DBMS
Presence of Data integrity.
 Data integrity makes unification of so many files into a single file. DBMS allows data
integrity which makes it easy to decrease data duplicity Data integration and reduces
redundancy as well as data inconsistency.
Support multiple users.
 DBMS allows multiple users to access the same database at a time without any
conflicts.
Avoidance of inconsistency.
 DBMS controls data redundancy and also controls data consistency. Data consistency
is nothing but if you want to update data in any files then all the files should not be
updated again.
 In DBMS, data is stored in a single database so data becomes more consistent in
comparison to file processing systems.
ADVANTAGES OF DBMS
Shared data
 Data can be shared between authorized users of the database in DBMS. All the users
have their own right to access the database. Admin has complete access to the
database. He has a right to assign users to access the database.
Enforcement of standards
 As DBMS have central control of the database. So, a DBA can ensure that all the
applications follow some standards such as format of data, document standards etc.
These standards help in data migrations or in interchanging the data.
Any unauthorized access is restricted
 Unauthorized persons are not allowed to access the database because of security
credentials.
ADVANTAGES OF DBMS
Provide backup of data
 Data loss is a big problem for all the organizations. In the file system users have to
back up the files in regular intervals which lead to waste of time and resources.
 DBMS solves this problem of taking backup automatically and recovery of the
database.
Tunability
 Tuning means adjusting something to get a better performance. Same in the case of
DBMS, as it provides tunability to improve performance. DBA adjusts databases to
get effective results.
DISADVANTAGES OF DBMS
Higher impact of a failure
 The centralization of resources increases the vulnerability of the system because all
users and applications rely on the availability of DBMS, the failure of any component
can bring operation to halt.
Cost of DBMS
 The cost of DBMS varies significantly depending on the environment and functionality
provided. There is also the recurrent annual maintenance cost.
THANK YOU