Logical Database Design Database Design

Running head: DATABASE SYSTEM AND DESIGN
Database System and Design
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DATABASE SYSTEM AND DESIGN
Introduction
A database is a system that helps to manage a set of related information. It can be defined as a
collection of coherent and meaningful data. In an organization multiple users are included
and they share the same recourses. So most of the data is stored repeatedly. Storing same data
multiple times is termed as redundancy which gives several problem such as problame in
updating records, wastage of memory that causes data inconsistency. To maintain large
amount of data in a well-organized manner by using the database approach.
In early days, the applications of the database systems were directly built based on the
traditional file systems. All the system records are stored into files. The traditional operating
system supports the file-processing systems. But the traditional file processing system has
certain disadvantages such as, data inconstancy, data redundancy, accessing data are difficult,
data isolation (different files, formats), integrity problems like insert, modify or delete
constraints, atomicity problem, simultaneous accessing of database by several users, security
problems. The database system provide solutions to overcome all those problems.

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DATABASE SYSTEM AND DESIGN
A conceptual database design for ABC’s bookings database system
EER Diagram
 An entity set or an attribute is used to represents an object.
 Strong and weak entity set are used to represent strong entities and weak entities.
 Generalization and specialization is used for modularity in the database designing.
 Use of binary relations and ternary relations.
 Use of aggregation-aggregate each entity set into a single unit, without having the
details of the internal storage-structure of the database.
 This provides the way to express a real world concept by a relationship set or by a set
of entities.
Reduced Relational Schemas
 Each schema consists of multiple columns generally associated with attributes with
unique names.
 Primary key can be used to define a set of entity and their relationship to express the
content of the database.
 The set of database schemas are used to represent an ER diagram.
 Each entity set has their unique schemas that is associated with corresponding
relationship set or entity set.

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DATABASE SYSTEM AND DESIGN
Logical Database Design
Database Design
These are the following steps when designing a database:
 Physical Design - the physical design describes the physical storage structure for the
database system.
 Logical designing - the logical designing describes the database schemas.
 Conceptual designing - the conceptual designing converts the user requirements to the
conceptual schema.
 User requirements - interactive database can be associated with domains from the
requirement specification of the user.
Entity: Client

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DATABASE SYSTEM AND DESIGN
Column Name Data Type Size Attributes
Client_Id varchar2 6 Primary key ‘first
letter must be C’
FullName varchar2 20 Not Null
Address varchar2 20 Not Null
MobileNo number 20 Not Null
Email varchar2 30 Not Null
Username varchar2 20 Not Null
Password varchar2 10 Not Null
Entity: Room
Column Name Data Type Size Attributes
Room_No varchar2 6 Primary key ‘first
letter must be R’
Room_Type varchar2 20 Not Null
Room_Price varchar2 20 Not Null
Description number 30 Not Null
Entity: Administration
Column Name Data Type Size Attributes
Staff_Id varchar2 6 Primary key ‘first
letter must be S’

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DATABASE SYSTEM AND DESIGN
StaffName varchar2 20 Not Null
Username varchar2 20 Not Null
Password varchar2 30 Not Null
Entity: Guest
Column Name Data Type Size Attributes
Guest _Id varchar2 6 Primary key ‘first
letter must be S’
GuestName varchar2 20 Not Null
No_ Guest number 10 Not Null
Entity: Event
Column Name Data Type Size Attributes
Event _Id varchar2 6 Primary key ‘first
letter must be E’
Event_Name varchar2 20 Not Null