W2: Information Management Concepts and •Control of data redundancy
Fundamentals
•Enforcement of integrity constraints
File Systems - are used by a manager of any small
•Restriction of unauthorized access
organization to track necessary data
•Data independence
Disadvantages: Lengthy development time; Difficulty of
getting quick answers; Complex system administration; •Backup and recovery facilities
Lack of security and limited data sharing; Extensive
Programming
Five Major Parts of a Database System: Hardware; Information Management
Software : OS Software.. DBMS Software… Application The infrastructure used to collect, manage, preserve,
programs and utility software; People: Systems store and deliver information
Administrators… Database Administrators… Database
Designers.. Systems Analysts and Programmers.. End The guiding principles that allow information to be
users; Procedures; Data available to the right people at the right time
Database- • is a shared collection of related data The view that all information, both digital and
used to support the activities of a particular physical, is an asset that requires proper management
organization. The organizational and social contexts in which
• can be viewed as a repository of data that is information exists
defined once and then accessed by various users
A database has the following properties: • Is an umbrella term that encompasses all the systems
•It is a representation of some aspect of the real world and processes within an organization for the creation
or a collection of data elements (facts) representing and use of corporate information
real- world information. • More than just technology; it is about the business
•A database is logical, coherent and internally processes and practices that underpin the creation and
consistent. use of information
•A database is designed, built and populated with data • It is also about the information itself, including the
for a specific purpose. structure of information (“information
•Each data item is stored in a field. architecture”), metadata, content quality, and more.
•A combination of fields makes up a table. For example, Purpose of Information Management • Design,
each field in an employee table contains data about an develop, manage, and use information with insight and
individual employee. innovation
Database Management System - is a collection of • Support decision making and create value for
programs that manages the database structure and individuals, organizations, communities, and societies
control access to the data stored in the database … A.
Traditional Banking System B. Bank DBMS
Characteristics and Benefits of a Database
•Self-describing nature of a database system
•Insulation between program and data
•Support for multiple views of data
•Sharing of data and multiuser system
W3: Database SystemConcepts and Architecture Three-Schema Architecture (3 Levels)
Data Model -A collection of concepts that can be used 1. Physical Level 2. Conceptual Level 3. External Level
to describe the structure of a database – provides the
necessary means to achieve data abstraction Data Independence--- The capacity to change the
schema at one level of a database system without
Data Abstraction - Refers to the suppression of details having to change the schema at the next higher level
of data organization and storage, and the highlighting
of the essential features for an improved Two Types of Data Independence
understanding of data
1. Logical Data Independence 2. Physical Data
Independence
Three Categories of Data Models According to Types of
Concepts Used in Describing Database Structure:
Week 4: Data Languages and Interfaces
1. High-level or Conceptual Data Models
Database Languages
2. Low-level or Physical Data Models
•Used to create and maintain database
3. Representational or Implementation Data Models
Data Definition Language (DDL)
Data Manipulation Language (DML)
Schemas and Instances
Data Control Language (DCL)
Database Schema- the description of the database--
includes descriptions of the database structure, data Data Query Language (DQL)
types, and the constraints on the database
Schema Diagram- An illustrative display of (most
Types of DML
aspects of) a database schema
High-Level or Non-procedural Language
Schema Construct- A component of the schema or an
object within the schema e.g STUDENT, COURSE For example, the SQL relational language
Database state: The actual data stored in a database at Are “set”-oriented and specify what data to retrieve
a particular moment in time. This includes the collection rather than how to retrieve it.
of all the data in the database. Also called database
instance (or occurrence or snapshot). Also called declarative languages
Database state- Refers to the content of a database at a Low Level or Procedural Language
moment in time Retrieve data one record-at-a-time
Initial Database State- Refers to the database state Constructs such as looping are needed to retrieve
when it is initially loaded into the system multiple records, along with positioning pointers
Valid State- A state that satisfies the structure and DBMS Interfaces
constraints of the database
Interfaces- A set of commands or menus through which
Distinction- The database schema changes very a user communicates with a program
infrequently---- The database state changes every time
the database is updated Menu-based Interfaces for Web Clients or Browsing
Forms-based Interfaces
Schema is also called intension Graphical User Interfaces
State is also called extension Natural Language Interfaces
Speech Input and Output
Interfaces for the DBA
Centralized DBMS - Combine everything into single Three Tier Client-Server Architecture
system including – DBMS software, hardware,
Common for Web applications
application programs, and user interface processing
software •User can still connect through a remote Intermediate Layer called Application Server or Web
terminal-however, all processing is done at centralized Server: 1. Stores the web connectivity software and the
site business logic part of the application used to access the
corresponding data from the database server 2. Acts
A Physical Centralized Architectures
like a conduit for sending partially processed data
Basic 2-tier Client-Server Architectures between the database server and the client
• Specialized Servers with Specialized Functions • Print Three-tier Architecture can enhance security
server • File server • DBMS server • Web server • Email
Database server only accessible via middle tier
server • Clients can access the specialized servers as
needed Clients cannot directly access database server
Logical two-tier client server architecture Classifications of DBMS
Based on the data model used :
Clients 1. Provide appropriate interfaces through a • Traditional: Relational, Network, Hierarchical
client software module to access and utilize the various
server resources 2. Clients may be diskless machines or • Emerging: Object-Oriented, Object-relational
PCs or Workstations with disks with only the client Other classifications
software installed 3. Connected to the servers via some
form of a network 4. LAN: local area network, wireless • Single-user (typically used with personal
network, etc. computers) vs. Multi-user (most DBMS)
DBMS Server • Centralized (uses a single computer with one
database) vs. Distributed (uses multiple computers,
Provides database query and transaction services to multiple databases)
the clients
Relational DBMS servers are often called SQL servers,
query servers, or transaction servers Database Models- the architecture that the DBMS uses
to store objects within the database and relate them to
Applications running on clients utilize an Application one another
Program Interface (API) to access server databases via
standard interface such as: ODBC: Open Database Hierarchical Model
Connectivity standard … JDBC: for Java programming Network Model
access
Relational Model
Client and server must install appropriate client
module and server module software for ODBC or JDBC Object-Oriented Model
Object-Relational Model
Two Tier Client-Server Architecture
A client program may connect to several DBMS,
sometimes called the data sources
Data sources can be files or other non-DBMS software
that manages data
Other variations of clients are possible
W5: ENTITY-RELATIONSHIP DIAGRAM Types of Relationship
ER Model One-to-one - One entity from entity set A can be
associated with at most one entity of entity
• introduced by Peter Chen in 1971
One-to-many - One entity from entity set A can be
• yields a graphical representation of entities and their
associated with more than one entities of entity set B
relationships in database structure
however an entity from entity set B, can be associated
• usually represented by an Entity Relationship Diagram with at most one entity.
• based on the following components: Many-to-one- More than one entities from entity set A
can be associated with at most one entity of entity set
Entity Attributes Relationship B, however an entity from entity set B can be
Components of ER Model associated with more than one entity from entity set
Entity- Can be a real-world object, either animate or Many-to-many- One entity from A can be associated
inanimate, that can easily identifiable with more than one entity from B and vice versa.
• Entity Set- Is a collection of similar types of entities…. • Cardinality- specifies how many instances of an entity
May contain entities with attribute sharing similar relate to one instance of another entity
values… Need not be disjoint • Cardinality Notations
Entity-Set and Keys Crow’s Foot Notation Bachman Style Martin Style
• Super Key − A set of attributes (one or more) that ER Diagram
collectively identifies an entity in an entity set. • can express the overall logical structure of a database
• Candidate Key − A minimal super key is called a in a graphical way
candidate key. An entity set may have more than one • uses graphic representations to model the database
candidate key. components
• Primary Key − A primary key is one of the candidate • Components of an ER Diagram
keys chosen by the database designer to uniquely
identify the entity set.
Relationship- describe the association among entities
Attributes • characteristic of an entity • All attributes
have values
Types of Attributes
Simple attribute Composite attribute
Derived attribute Single-value attribute
Multi-value attribute
Entity - Entities are represented by means of rectangles.
Rectangles are named with the entity set they
represent. • The term entity is often used instead of
“table” • Think of them as nouns
Attributes- Attributes are the properties of entities.
Attributes are represented by means of ellipses.
• If the attributes are composite, they are further
divided in a tree like structure.
• Multivalued attributes are depicted by double ellipse.
• Derived attributes are depicted by dashed ellipse.
Relationship- Relationships are represented by
diamond-shaped box. Name of the relationship is
written inside the diamond-box. All the entities
(rectangles) participating in a relationship, are
connected to it by a line.
Generalization-- a number of entities are brought
together into one generalized entity based on their
similar characteristics.
Specialization- is the opposite of generalization. In
specialization, a group of entities is divided into sub-
groups based on their characteristics.
Steps to Create an ERD
Entity Identification > Relationship Identification >
Cardinality Identification > Identify Attributes > Create
ERD
3 Levels of Abstraction
Conceptual .. Logical… Physical Data Model
CRUD -create, read, update, and delete
In computer programming, create, read, update,
and delete (CRUD) are the four basic functions of
persistent storage. Alternate words are sometimes
used when defining the four basic functions of
CRUD, such as retrieve instead of read, modify
instead of update, or destroy instead of delete
