Overview, Database System vs File System, Database System Concept and
Architecture, Data Model Schema and Instances, Data Independence and Database Language and
Interfaces, Data Definitions Language, DML, Overall Database Structure. Data Modeling Using the
Entity Relationship Model: ER Model Concepts, Notation for ER Diagram, Mapping Constraints,
Keys, Concepts of Super Key, Candidate Key, Primary Key, Generalization, Aggregation,
Reduction of an ER Diagrams to Tables, Extended ER Model, Relationship of Higher Degree.
ESOFT Metro Campus - Diploma in Software Engineering - (Module IV) Database Concepts
(Template - Virtusa Corporate)
Contents:
Introduction to Databases
Data
Information
Database
Database System
Database Applications
Evolution of Databases
Traditional Files Based Systems
Limitations in Traditional Files
The Database Approach
Advantages of Database Approach
Disadvantages of Database Approach
Database Management Systems
DBMS Functions
Database Architecture
ANSI-SPARC 3 Level Architecture
The Relational Data Model
What is a Relation?
Primary Key
Cardinality and Degree
Relationships
Foreign Key
Data Integrity
Data Dictionary
Database Design
Requirements Collection and analysis
Conceptual Design
Logical Design
Physical Design
Entity Relationship Model
A mini-world example
Entities
Relationships
ERD Notations
Cardinality
Optional Participation
Entities and Relationships
Attributes
Entity Relationship Diagram
Entities
ERD Showing Weak Entities
Super Type / Sub Type Relationships
Mapping ERD to Relational
Map Regular Entities
Map Weak Entities
Map Binary Relationships
Map Associated Entities
Map Unary Relationships
Map Ternary Relationships
Map Supertype/Subtype Relationships
Normalization
Advantages of Normalization
Disadvantages of Normalization
Normal Forms
Functional Dependency
Purchase Order Relation in 0NF
Purchase Order Relation in 1NF
Purchase Order Relations in 2NF
Purchase Order Relations in 3NF
Normalized Relations
BCNF – Boyce Codd Normal Form
Structured Query Language
What We Can Do with SQL ?
SQL Commands
SQL CREATE DATABASE
SQL CREATE TABLE
SQL DROP
SQL Constraints
SQL NOT NULL
SQL PRIMARY KEY
SQL CHECK
SQL FOREIGN KEY
SQL ALTER TABLE
SQL INSERT INTO
SQL INSERT INTO SELECT
SQL SELECT
SQL SELECT DISTINCT
SQL WHERE
SQL AND & OR
SQL ORDER BY
SQL UPDATE
SQL DELETE
SQL LIKE
SQL IN
SQL BETWEEN
SQL INNER JOIN
SQL LEFT JOIN
SQL RIGHT JOIN
SQL UNION
SQL AS
SQL Aggregate Functions
SQL Scalar functions
SQL GROUP BY
SQL HAVING
Database Administration
SQL Database Administration
Relations can be represented as two-dimensional data tables with rows and columns. The rows of a relation are called tuples.
The columns of a relation are called attributes. The attributes draw values from a domain (a legal pool of values).
This presentation delivered for undergraduate students under the university relations programme of 99X Technology. This presentation covers basic concepts of Unified Modelling Language including some hands-on activities.
Dbms classification according to data modelsABDUL KHALIQ
CLASSIFICATION ACCORDING TO DATA MODELS
Hierarchal Model
In a hierarchical data model, data are organized into a tree-like structure.
Network Model
based on an enlargement of the concept of hierarchical data bases.
Relational Model
Data are stored in tables
Object Oriented model
Object oriented data base systems are the most recent development in data base technology.
Introduction
Definations
Advantages and Disadvantages
PowerPoint Presentation
PowerPoint Presentation for free
Relational data base management system (Unit 1)Ismail Mukiibi
Introduction to Relational database management system, A definition of an RDBMS is a DBMS in which data is stored in tables and the relationships among the data are also stored in tables. The data can be accessed or reassembled in many different ways without having to change the table forms.
ESOFT Metro Campus - Diploma in Software Engineering - (Module IV) Database Concepts
(Template - Virtusa Corporate)
Contents:
Introduction to Databases
Data
Information
Database
Database System
Database Applications
Evolution of Databases
Traditional Files Based Systems
Limitations in Traditional Files
The Database Approach
Advantages of Database Approach
Disadvantages of Database Approach
Database Management Systems
DBMS Functions
Database Architecture
ANSI-SPARC 3 Level Architecture
The Relational Data Model
What is a Relation?
Primary Key
Cardinality and Degree
Relationships
Foreign Key
Data Integrity
Data Dictionary
Database Design
Requirements Collection and analysis
Conceptual Design
Logical Design
Physical Design
Entity Relationship Model
A mini-world example
Entities
Relationships
ERD Notations
Cardinality
Optional Participation
Entities and Relationships
Attributes
Entity Relationship Diagram
Entities
ERD Showing Weak Entities
Super Type / Sub Type Relationships
Mapping ERD to Relational
Map Regular Entities
Map Weak Entities
Map Binary Relationships
Map Associated Entities
Map Unary Relationships
Map Ternary Relationships
Map Supertype/Subtype Relationships
Normalization
Advantages of Normalization
Disadvantages of Normalization
Normal Forms
Functional Dependency
Purchase Order Relation in 0NF
Purchase Order Relation in 1NF
Purchase Order Relations in 2NF
Purchase Order Relations in 3NF
Normalized Relations
BCNF – Boyce Codd Normal Form
Structured Query Language
What We Can Do with SQL ?
SQL Commands
SQL CREATE DATABASE
SQL CREATE TABLE
SQL DROP
SQL Constraints
SQL NOT NULL
SQL PRIMARY KEY
SQL CHECK
SQL FOREIGN KEY
SQL ALTER TABLE
SQL INSERT INTO
SQL INSERT INTO SELECT
SQL SELECT
SQL SELECT DISTINCT
SQL WHERE
SQL AND & OR
SQL ORDER BY
SQL UPDATE
SQL DELETE
SQL LIKE
SQL IN
SQL BETWEEN
SQL INNER JOIN
SQL LEFT JOIN
SQL RIGHT JOIN
SQL UNION
SQL AS
SQL Aggregate Functions
SQL Scalar functions
SQL GROUP BY
SQL HAVING
Database Administration
SQL Database Administration
Relations can be represented as two-dimensional data tables with rows and columns. The rows of a relation are called tuples.
The columns of a relation are called attributes. The attributes draw values from a domain (a legal pool of values).
This presentation delivered for undergraduate students under the university relations programme of 99X Technology. This presentation covers basic concepts of Unified Modelling Language including some hands-on activities.
Dbms classification according to data modelsABDUL KHALIQ
CLASSIFICATION ACCORDING TO DATA MODELS
Hierarchal Model
In a hierarchical data model, data are organized into a tree-like structure.
Network Model
based on an enlargement of the concept of hierarchical data bases.
Relational Model
Data are stored in tables
Object Oriented model
Object oriented data base systems are the most recent development in data base technology.
Introduction
Definations
Advantages and Disadvantages
PowerPoint Presentation
PowerPoint Presentation for free
Relational data base management system (Unit 1)Ismail Mukiibi
Introduction to Relational database management system, A definition of an RDBMS is a DBMS in which data is stored in tables and the relationships among the data are also stored in tables. The data can be accessed or reassembled in many different ways without having to change the table forms.
These slides cover the following concepts:
~ RDBMS vs DBMS
~ RDBMS structure
~ RDBMS basics for beginners
~ RELATIONAL DATABASE MANAGEMENT SYSTEM
~ DATA, SCHEMA, AND DATABASE
~ WHAT IS RDBMS?
~ FEATURES OF RDBMS
~ RELATIONSHIPS IN DATABASE
~ RULES OF RDBMS
~ ELEMENTS OF RDBMS
~ SQL COMMANDS
~ SQL CONSTRAINTS
~ COMMON SQL CONSTRAINTS
~ DATA DEFINITION LANGUAGE SCRIPT (DDL)
~ DATA MANIPULATION LANGUAGE SCRIPT (DML)
~ DATA CONTROL LANGUAGE SCRIPT (DCL)
~ PRIMARY KEY, FOREIGN KEY
~ EXAMPLE OF PRIMARY AND FOREIGN KEY
~ DBMS VS RDBMS
~ RDBMS NORMALIZATION
~ BENEFITS OF NORMALIZING
~ SQL JOINS
~ INNER JOIN
~ LEFT OUTER JOIN
~ RIGHT OUTER JOIN
~ FULL OUTER JOIN
~ CROSS JOIN
~ SELF JOIN
Database means collection of inter-related data and relationships among those data. dbms means set of programs to access those data. The structure of dbms contains two components, They query processor and storage manager.
These slides cover the following concepts:
~ RDBMS vs DBMS
~ RDBMS structure
~ RDBMS basics for beginners
~ RELATIONAL DATABASE MANAGEMENT SYSTEM
~ DATA, SCHEMA, AND DATABASE
~ WHAT IS RDBMS?
~ FEATURES OF RDBMS
~ RELATIONSHIPS IN DATABASE
~ RULES OF RDBMS
~ ELEMENTS OF RDBMS
~ SQL COMMANDS
~ SQL CONSTRAINTS
~ COMMON SQL CONSTRAINTS
~ DATA DEFINITION LANGUAGE SCRIPT (DDL)
~ DATA MANIPULATION LANGUAGE SCRIPT (DML)
~ DATA CONTROL LANGUAGE SCRIPT (DCL)
~ PRIMARY KEY, FOREIGN KEY
~ EXAMPLE OF PRIMARY AND FOREIGN KEY
~ DBMS VS RDBMS
~ RDBMS NORMALIZATION
~ BENEFITS OF NORMALIZING
~ SQL JOINS
~ INNER JOIN
~ LEFT OUTER JOIN
~ RIGHT OUTER JOIN
~ FULL OUTER JOIN
~ CROSS JOIN
~ SELF JOIN
Database means collection of inter-related data and relationships among those data. dbms means set of programs to access those data. The structure of dbms contains two components, They query processor and storage manager.
CHAPTER 1 Database system architecture.pptxkashishy2
Database system Architecure...Topic from DBMS subaject unit 1 ..
Outline:
Introduction of DBMS
Applications of DBMS
Advantages of DBMS
Data Abstraction,
Data Independence,
Data Definition Language (DDL),
Data Manipulation Language (DML).
all above topics are covred in this chapter.
Concurrency Control Techniques: Concurrency Control, Locking Techniques for Concurrency
Control, Time Stamping Protocols for Concurrency Control, Validation Based Protocol, Multiple
Granularity, Multi Version Schemes, Recovery with Concurrent Transaction,
Data Base Design & Normalization: Functional dependencies, normal forms, first, second, 8 third
normal forms, BCNF, inclusion dependence, loss less join decompositions, normalization using
FD, MVD, and JDs, alternative approaches to database design
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
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An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
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Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
2. What is Database?
• The database is a collection of inter-related data
which is used to retrieve, insert and delete the
data efficiently. It is also used to organize the data
in the form of a table, schema, views, and
reports, etc.
• For example: The college Database organizes the
data about the admin, staff, students and faculty
etc.
• Using the database, you can easily retrieve,
insert, and delete the information.
3. Database Management System
• Database management system is a software which is used to manage the
database. For example: MySQL, Oracle, etc are a very popular commercial
database which is used in different applications.
• DBMS provides an interface to perform various operations like database creation,
storing data in it, updating data, creating a table in the database and a lot more.
• It provides protection and security to the database. In the case of multiple users, it
also maintains data consistency.
• DBMS allows users the following tasks:
• Data Definition: It is used for creation, modification, and removal of definition that
defines the organization of data in the database.
• Data Updation: It is used for the insertion, modification, and deletion of the actual
data in the database.
• Data Retrieval: It is used to retrieve the data from the database which can be used
by applications for various purposes.
• User Administration: It is used for registering and monitoring users, maintain data
integrity, enforcing data security, dealing with concurrency control, monitoring
performance and recovering information corrupted by unexpected failure.
4. Characteristics of DBMS
• It uses a digital repository established on a server to store
and manage the information.
• It can provide a clear and logical view of the process that
manipulates data.
• DBMS contains automatic backup and recovery procedures.
• It contains ACID properties which maintain data in a
healthy state in case of failure.
• It can reduce the complex relationship between data.
• It is used to support manipulation and processing of data.
• It is used to provide security of data.
• It can view the database from different viewpoints
according to the requirements of the user.
5. Advantages of DBMS
• Controls database redundancy: It can control data redundancy
because it stores all the data in one single database file and that
recorded data is placed in the database.
• Data sharing: In DBMS, the authorized users of an organization can
share the data among multiple users.
• Easily Maintenance: It can be easily maintainable due to the
centralized nature of the database system.
• Reduce time: It reduces development time and maintenance need.
• Backup: It provides backup and recovery subsystems which create
automatic backup of data from hardware and software failures and
restores the data if required.
• Multiple user interface: It provides different types of user
interfaces like graphical user interfaces, application program
interfaces
6. Disadvantages of DBMS
• Cost of Hardware and Software: It requires a high
speed of data processor and large memory size to run
DBMS software.
• Size: It occupies a large space of disks and large
memory to run them efficiently.
• Complexity: Database system creates additional
complexity and requirements.
• Higher impact of failure: Failure is highly impacted the
database because in most of the organization, all the
data stored in a single database and if the database is
damaged due to electric failure or database corruption
then the data may be lost forever.
7. DBMS Architecture
• The DBMS design depends upon its architecture.
The basic client/server architecture is used to
deal with a large number of PCs, web servers,
database servers and other components that are
connected with networks.
• The client/server architecture consists of many
PCs and a workstation which are connected via
the network.
• DBMS architecture depends upon how users are
connected to the database to get their request
done.
9. Types of DBMS Architecture
1-Tier Architecture
• In this architecture, the database is directly available to the user. It means the user
can directly sit on the DBMS and uses it.
• Any changes done here will directly be done on the database itself. It doesn't
provide a handy tool for end users.
• The 1-Tier architecture is used for development of the local application, where
programmers can directly communicate with the database for the quick response.
2-Tier Architecture
• The 2-Tier architecture is same as basic client-server. In the two-tier architecture,
applications on the client end can directly communicate with the database at the
server side. For this interaction, API's like: ODBC, JDBC are used.
• The user interfaces and application programs are run on the client-side.
• The server side is responsible to provide the functionalities like: query processing
and transaction management.
• To communicate with the DBMS, client-side application establishes a connection
with the server side.
11. 3-Tier Architecture
• The 3-Tier architecture contains another layer between
the client and server. In this architecture, client can't
directly communicate with the server.
• The application on the client-end interacts with an
application server which further communicates with
the database system.
• End user has no idea about the existence of the
database beyond the application server. The database
also has no idea about any other user beyond the
application.
• The 3-Tier architecture is used in case of large web
application.
13. Three schema Architecture
• The three schema architecture is also called
ANSI/SPARC architecture or three-level
architecture.
• This framework is used to describe the structure
of a specific database system.
• The three schema architecture is also used to
separate the user applications and physical
database.
• The three schema architecture contains three-
levels. It breaks the database down into three
different categories.
15. Data Models
• Data Model is the modeling of the data description, data semantics, and
consistency constraints of the data.
• It provides the conceptual tools for describing the design of a database at
each level of data abstraction
16. Data Models
• 1) Relational Data Model: This type of model designs
the data in the form of rows and columns within a
table. Thus, a relational model uses tables for
representing data and in-between relationships. Tables
are also called relations. This model was initially
described by Edgar F. Codd, in 1969.
• 2) Entity-Relationship Data Model: An ER model is the
logical representation of data as objects and
relationships among them. These objects are known as
entities, and relationship is an association among these
entities. This model was designed by Peter Chen and
published in 1976 papers. It was widely used in
database designing.
17. • 3) Object-based Data Model: An extension of the ER model
with notions of functions, encapsulation, and object
identity, as well. This model supports a rich type system
that includes structured and collection types. Thus, in
1980s, various database systems following the object-
oriented approach were developed. Here, the objects are
nothing but the data carrying its properties.
• 4) Semistructured Data Model: This type of data model is
different from the other three data models (explained
above). The semistructured data model allows the data
specifications at places where the individual data items of
the same type may have different attributes sets.
18. Data model Schema and Instance
• The data which is stored in the database at a particular moment of
time is called an instance of the database.
• The overall design of a database is called schema.
• A database schema is the skeleton structure of the database. It
represents the logical view of the entire database.
• A schema contains schema objects like table, foreign key, primary
key, views, columns, data types, stored procedure, etc.
• A database schema can be represented by using the visual diagram.
That diagram shows the database objects and relationship with
each other.
• A database schema is designed by the database designers to help
programmers whose software will interact with the database. The
process of database creation is called data modeling.
19. Data Independence
• Data independence can be explained using the three-schema architecture.
• Data independence refers characteristic of being able to modify the schema at one level of
the database system without altering the schema at the next higher level.
• There are two types of data independence:
1. Logical Data Independence
• Logical data independence refers characteristic of being able to change the conceptual
schema without having to change the external schema.
• Logical data independence is used to separate the external level from the conceptual view.
• If we do any changes in the conceptual view of the data, then the user view of the data
would not be affected.
• Logical data independence occurs at the user interface level.
2. Physical Data Independence
• Physical data independence can be defined as the capacity to change the internal schema
without having to change the conceptual schema.
• If we do any changes in the storage size of the database system server, then the Conceptual
structure of the database will not be affected.
• Physical data independence is used to separate conceptual levels from the internal levels.
• Physical data independence occurs at the logical interface level.
21. Database Language
• A DBMS has appropriate languages and interfaces to express
database queries and updates.
• Database languages can be used to read, store and update the
data in the database.
• Types of Database Language
22. Keys
• Keys play an important role in the relational database.
• It is used to uniquely identify any record or row of data from the table. It is
also used to establish and identify relationships between tables.
• For example: In Student table, ID is used as a key because it is unique for
each student. In PERSON table, passport_number, license_number, SSN
are keys since they are unique for each person.
•
23. Types of key:
1. Primary key
•It is the first key which is used to identify one and only one instance of an entity
uniquely. An entity can contain multiple keys as we saw in PERSON table. The key
which is most suitable from those lists become a primary key.
•In the EMPLOYEE table, ID can be primary key since it is unique for each employee.
In the EMPLOYEE table, we can even select License_Number and Passport_Number as
primary key since they are also unique.
•For each entity, selection of the primary key is based on requirement and
developers.
24. 2. Candidate key
• A candidate key is an attribute or set of an attribute which can uniquely
identify a tuple.
• The remaining attributes except for primary key are considered as a
candidate key. The candidate keys are as strong as the primary key.
• For example: In the EMPLOYEE table, id is best suited for the primary key.
Rest of the attributes like SSN, Passport_Number, and License_Number,
etc. are considered as a candidate key.
25. 3. Super Key
• Super key is a set of an attribute which can uniquely
identify a tuple. Super key is a superset of a
candidate key.
• For example: In the above EMPLOYEE table,
for(EMPLOEE_ID, EMPLOYEE_NAME) the name of
two employees can be the same, but their
EMPLYEE_ID can't be the same. Hence, this
combination can also be a key.
• The super key would be EMPLOYEE-ID,
(EMPLOYEE_ID, EMPLOYEE-NAME), etc.
26. 4. Foreign key
• Foreign keys are the column of the table which is used to point to the primary key of another table.
• In a company, every employee works in a specific department, and employee and department are two
different entities. So we can't store the information of the department in the employee table. That's why
we link these two tables through the primary key of one table.
• We add the primary key of the DEPARTMENT table, Department_Id as a new attribute in the EMPLOYEE
table.
• Now in the EMPLOYEE table, Department_Id is the foreign key, and both the tables are related.
27. Generalization
• Generalization is like a bottom-up approach in which two or more entities
of lower level combine to form a higher level entity if they have some
attributes in common.
• In generalization, an entity of a higher level can also combine with the
entities of the lower level to form a further higher level entity.
• Generalization is more like subclass and superclass system, but the only
difference is the approach. Generalization uses the bottom-up approach.
28. Specialization
• Specialization is a top-down approach, and it is opposite to Generalization. In
specialization, one higher level entity can be broken down into two lower level
entities.
• Specialization is used to identify the subset of an entity set that shares some
distinguishing characteristics.
• Normally, the superclass is defined first, the subclass and its related attributes are
defined next, and relationship set are then added.
• For example: In an Employee management system, EMPLOYEE entity can be
specialized as TESTER or DEVELOPER based on what role they play in the company.
•
29. Aggregation
• In aggregation, the relation between two entities is treated as a single entity. In
aggregation, relationship with its corresponding entities is aggregated into a higher
level entity.
• For example: Center entity offers the Course entity act as a single entity in the
relationship which is in a relationship with another entity visitor. In the real world,
if a visitor visits a coaching center then he will never enquiry about the Course
only or just about the Center instead he will ask the enquiry about both.
30. Reduction of ER diagram to Table
• The database can be represented using the notations, and these notations can be
reduced to a collection of tables.
• In the database, every entity set or relationship set can be represented in tabular
form.The ER diagram is given below:
32. • Defining the information.
• Storing the information.
• Manipulating the information.
• Protecting the information from system crashes or data
theft.
• Differentiating access permissions for different users.
The database system is divided into three components:
Query Processor, Storage Manager, and Disk Storage.
These are explained as following below.
33. 1. Query Processor :
•
It interprets the requests (queries) received from end user via an application program into
instructions. It also executes the user request which is received from the DML compiler.
Query Processor contains the following components –
• DML Compiler –
It processes the DML statements into low level instruction (machine language), so that they
can be executed.
• DDL Interpreter –
It processes the DDL statements into a set of table containing meta data (data about data).
• Embedded DML Pre-compiler –
It processes DML statements embedded in an application program into procedural calls.
• Query Optimizer –
It executes the instruction generated by DML Compiler.
34. 2. Storage Manager :
• Storage Manager is a program that provides an interface between the data
stored in the database and the queries received.
• It is also known as Database Control System.
• It maintains the consistency and integrity of the database by applying the
constraints and executes the DCL statements.
• It is responsible for updating, storing, deleting, and retrieving data in the
database.
It contains the following components –
• Authorization Manager –
It ensures role-based access control, i.e,. checks whether the particular person is
privileged to perform the requested operation or not.
• Integrity Manager –
It checks the integrity constraints when the database is modified.
35. 2. Storage Manager :
• Transaction Manager –
It controls concurrent access by performing the operations
in a scheduled way that it receives the transaction. Thus, it
ensures that the database remains in the consistent state
before and after the execution of a transaction.
• File Manager –
It manages the file space and the data structure used to
represent information in the database.
• Buffer Manager –
It is responsible for cache memory and the transfer of data
between the secondary storage and main memory.
36. 3. Disk Storage :
•
It contains the following components –
• Data Files –
It stores the data.
• Data Dictionary –
It contains the information about the structure of any database object. It
is the repository of information that governs the metadata.
• Indices –
It provides faster retrieval of data item.
•
37. Extended Entity-Relationship (EE-R) Model
• EER is a high-level data model that incorporates the extensions to
the original ER model. Enhanced ERD are high level models that
represent the requirements and complexities of complex database.
• In addition to ER model concepts EE-R includes −
• Subclasses and Super classes.
• Specialization and Generalization.
• Category or union type.
• Aggregation.
• These concepts are used to create EE-R diagrams.
• Subclasses and Super class
• Super class is an entity that can be divided into further subtype.
38. Extended Entity-Relationship (EE-R) Model
Super class shape has sub groups: Triangle, Square and Circle.
Sub classes are the group of entities with some unique attributes.Sub class
inherits the properties and attributes from super class.