Entity relation(1)
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Peter Chen developed entity-relationship (ER) diagrams in 1976 to model databases. ER diagrams use entities (objects), attributes (data about entities), and relationships (connections between entities) to represent the structure and semantics of data. Developing an ER diagram helps database designers and analysts better understand the information to be stored in a database by modeling the entities, attributes, and relationships visually.
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ER DIAGRAM & ER MODELING IN DBMS
An Entity–relationship model (ER model) describes the structure of a database with the help of a diagram, which is known as Entity Relationship Diagram (ER Diagram). An ER model is a design or blueprint of a database that can later be implemented as a database. The main components of E-R model are: entity set and relationship set
2. Entity Relationship Model in DBMS
The document provides an overview of entity-relationship (E-R) modeling concepts including:
- Entity sets represent collections of real-world entities that share common properties
- Relationship sets define associations between entity sets
- Attributes provide additional information about entities and relationships
- Keys uniquely identify entities and relationships
- Cardinalities constrain how entities can participate in relationships
- E-R diagrams visually depict entity sets, attributes, relationships and constraints.
entity-relationship-diagram-chen-&-crow -model.ppt
The document discusses entity relationship diagrams and how to model data using ER diagrams. It covers the key components of ER diagrams including entities, attributes, relationships and cardinality. Entities can be people, places, objects, events or concepts. Attributes are the properties of entities. Relationships show associations between entities. Cardinality specifies the minimum and maximum number of relationships between entities. The document provides examples and guidelines for properly constructing ER diagrams to model data without redundancy.
Entity Relationship Modelling
This document discusses entity relationship (ER) modeling. It defines key concepts in ER modeling including entities, attributes, relationships, and ER diagram notations. Entities can be people, places, objects or concepts and are grouped into entity types. Attributes provide information about entities. Relationships define how entities are connected. Common relationship types are one-to-one, one-to-many, many-to-one, and many-to-many. ER diagrams use notations like boxes, lines, and crow's foot symbols to visually depict entities, attributes, and relationships in a database design. The document also covers entity classification, primary keys, foreign keys, and potential problems in ER modeling.
DBMS: Types of keys
The document defines and provides examples of different types of keys used in database systems, including super keys, candidate keys, primary keys, alternate keys, composite keys, foreign keys, and unique keys. A super key can identify a tuple but contains extra attributes, while a candidate key is a minimal super key. The primary key is chosen by the administrator and must be unique. Alternate keys are other candidate keys, and composite keys comprise multiple attributes. Foreign keys link tables using primary keys, and unique keys are like primary keys but allow null values.
STRUCTURE OF SQL QUERIES
This document defines SQL data definition statements and basic SQL query structure. It discusses DDL statements like CREATE, ALTER, and DROP that are used to define and manage database structures. It also explains the typical components of an SQL query including the SELECT, FROM, and WHERE clauses. Finally, it outlines several set operations in SQL like UNION, UNION ALL, INTERSECT, and MINUS.
Relational Data Model Introduction
The document discusses the relational data model and query languages. It provides the following key points:
1. The relational data model organizes data into tables with rows and columns, where rows represent records and columns represent attributes. Relations between data are represented through tables.
2. Relational integrity constraints include key constraints, domain constraints, and referential integrity constraints to ensure valid data.
3. Relational algebra and calculus provide theoretical foundations for query languages like SQL. Relational algebra uses operators like select, project, join on relations, while relational calculus specifies queries using logic.
Types of keys in database management system by Dr. Kamal Gulati
Types of keys in database management system by Dr. Kamal GulatiAmity University | FMS - DU | IMT | Stratford University | KKMI International Institute | AIMA | DTU
The document discusses different types of keys used in database management systems. It defines keys as attributes that uniquely identify records in a database table. The main types of keys discussed are primary keys, candidate keys, alternate keys, composite keys, and foreign keys. Primary keys must be unique and cannot contain null values. Candidate keys are attributes that could serve as primary keys. Foreign keys link records between tables.Recommended
ER DIAGRAM & ER MODELING IN DBMS
An Entity–relationship model (ER model) describes the structure of a database with the help of a diagram, which is known as Entity Relationship Diagram (ER Diagram). An ER model is a design or blueprint of a database that can later be implemented as a database. The main components of E-R model are: entity set and relationship set
2. Entity Relationship Model in DBMS
The document provides an overview of entity-relationship (E-R) modeling concepts including:
- Entity sets represent collections of real-world entities that share common properties
- Relationship sets define associations between entity sets
- Attributes provide additional information about entities and relationships
- Keys uniquely identify entities and relationships
- Cardinalities constrain how entities can participate in relationships
- E-R diagrams visually depict entity sets, attributes, relationships and constraints.
entity-relationship-diagram-chen-&-crow -model.ppt
The document discusses entity relationship diagrams and how to model data using ER diagrams. It covers the key components of ER diagrams including entities, attributes, relationships and cardinality. Entities can be people, places, objects, events or concepts. Attributes are the properties of entities. Relationships show associations between entities. Cardinality specifies the minimum and maximum number of relationships between entities. The document provides examples and guidelines for properly constructing ER diagrams to model data without redundancy.
Entity Relationship Modelling
This document discusses entity relationship (ER) modeling. It defines key concepts in ER modeling including entities, attributes, relationships, and ER diagram notations. Entities can be people, places, objects or concepts and are grouped into entity types. Attributes provide information about entities. Relationships define how entities are connected. Common relationship types are one-to-one, one-to-many, many-to-one, and many-to-many. ER diagrams use notations like boxes, lines, and crow's foot symbols to visually depict entities, attributes, and relationships in a database design. The document also covers entity classification, primary keys, foreign keys, and potential problems in ER modeling.
DBMS: Types of keys
The document defines and provides examples of different types of keys used in database systems, including super keys, candidate keys, primary keys, alternate keys, composite keys, foreign keys, and unique keys. A super key can identify a tuple but contains extra attributes, while a candidate key is a minimal super key. The primary key is chosen by the administrator and must be unique. Alternate keys are other candidate keys, and composite keys comprise multiple attributes. Foreign keys link tables using primary keys, and unique keys are like primary keys but allow null values.
STRUCTURE OF SQL QUERIES
This document defines SQL data definition statements and basic SQL query structure. It discusses DDL statements like CREATE, ALTER, and DROP that are used to define and manage database structures. It also explains the typical components of an SQL query including the SELECT, FROM, and WHERE clauses. Finally, it outlines several set operations in SQL like UNION, UNION ALL, INTERSECT, and MINUS.
Relational Data Model Introduction
The document discusses the relational data model and query languages. It provides the following key points:
1. The relational data model organizes data into tables with rows and columns, where rows represent records and columns represent attributes. Relations between data are represented through tables.
2. Relational integrity constraints include key constraints, domain constraints, and referential integrity constraints to ensure valid data.
3. Relational algebra and calculus provide theoretical foundations for query languages like SQL. Relational algebra uses operators like select, project, join on relations, while relational calculus specifies queries using logic.
Types of keys in database management system by Dr. Kamal Gulati
Types of keys in database management system by Dr. Kamal GulatiAmity University | FMS - DU | IMT | Stratford University | KKMI International Institute | AIMA | DTU
The document discusses different types of keys used in database management systems. It defines keys as attributes that uniquely identify records in a database table. The main types of keys discussed are primary keys, candidate keys, alternate keys, composite keys, and foreign keys. Primary keys must be unique and cannot contain null values. Candidate keys are attributes that could serve as primary keys. Foreign keys link records between tables.ER-Model-ER Diagram
Here are the entity relationship diagrams and tables for the car insurance company database:
(a) E-R Diagram:
Person - owns - Car
(1:M)
Car - involved in - Accident
(0:M)
(b) Tables:
person
(driver_id primary key,
name, address)
car
(license primary key,
year, model, driver_id foreign key references person)
accident
(report_number primary key,
date, location)
participated
(driver_id foreign key references person,
license foreign key references car,
report_number foreign key references accident
Er to tables
The document discusses the process of logical database design, which involves converting conceptual models represented by entity-relationship (ER) diagrams into relational database tables. It describes how different types of relationships in ER diagrams, such as one-to-one, one-to-many, and many-to-many, translate to tables and foreign keys. The document also introduces data normalization as a process for structuring tables to eliminate redundancy among non-key attributes and provides examples of designing databases for different domains.
Database language
This document discusses database languages used in database management systems (DBMS). It describes three types of database languages: data definition language (DDL) used to define and modify the database schema; data manipulation language (DML) used to insert, update, delete and retrieve data; and data control language (DCL) used to control access privileges. Examples are provided for common statements in each language type like CREATE, ALTER, DROP for DDL and INSERT, UPDATE, DELETE, SELECT for DML. Case sensitivity and data types are also briefly covered.
FUNCTION DEPENDENCY AND TYPES & EXAMPLE
Functional dependency defines a relationship between attributes in a table where a set of attributes determine another attribute. There are different types of functional dependencies including trivial, non-trivial, multivalued, and transitive. An example given is a student table with attributes Stu_Id, Stu_Name, Stu_Age which has the functional dependency of Stu_Id->Stu_Name since the student ID uniquely identifies the student name.
Entity relationship modelling
This document provides an overview of entity-relationship modeling as a first step for designing a relational database. It describes how to model entities, attributes, relationships, and participation constraints. Key aspects covered include using boxes to represent entity types, diamonds for relationship types, and labeling relationships with degrees. The document also discusses handling multi-valued attributes and deciding whether to model concepts as attributes or entity types.
Entity Relationship Diagram
The document discusses the entity-relationship (E-R) data model. It defines key concepts in E-R modeling including entities, attributes, entity sets, relationships, and relationship sets. It describes different types of attributes and relationships. It also explains how to represent E-R diagrams visually using symbols like rectangles, diamonds, and lines to depict entities, relationships, keys, and cardinalities. Primary keys, foreign keys, and weak entities are also covered.
data modeling and models
This document provides an overview of data modeling, including definitions of key concepts like data models and data modeling. It describes the evolution of popular data models from hierarchical to network to relational to entity-relationship to object-oriented models. For each model, it outlines the basic concepts, advantages, and disadvantages. The document emphasizes that newer data models aimed to address shortcomings of previous approaches and capture real-world data and relationships.
Database Management System
The document discusses database management systems and their advantages over traditional file systems. It covers key concepts such as:
1) Databases organize data into tables with rows and columns to allow for easier querying and manipulation of data compared to file systems which store data in unstructured files.
2) Database management systems employ concepts like normalization, transactions, concurrency and security to maintain data integrity and consistency when multiple users are accessing the data simultaneously.
3) The logical design of a database is represented by its schema, while a database instance refers to the current state of the data stored in the database tables at a given time.
Relational algebra
The document discusses the topics covered in a database technologies course, including relational algebra operations. It provides examples and explanations of relational algebra concepts like selection, projection, join, union, difference, and cartesian product. It also discusses limitations of relational algebra in expressing complex queries involving transitive closure. The document contains practice questions related to relational algebra operations at the end.
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Normalisation is a process that structures data in a relational database to minimize duplication and redundancy while preserving information. It aims to ensure data is structured efficiently and consistently through multiple forms. The stages of normalization include first normal form (1NF), second normal form (2NF), third normal form (3NF), Boyce-Codd normal form (BCNF), fourth normal form (4NF) and fifth normal form (5NF). Higher normal forms eliminate more types of dependencies to optimize the database structure.
Dbms relational model
“A DBMS that manages data as collection of tables in which all data relationships are represented by common values in related tables.”
Entity Relationship Model
The document provides an overview of entity-relationship (ER) modeling concepts used in database design. It defines key terms like entities, attributes, relationships, and cardinalities. It explains how ER diagrams visually represent these concepts using symbols like rectangles, diamonds, and lines. The document also discusses entity types, relationship degrees, key attributes, weak entities, and how to model one-to-one, one-to-many, many-to-one, and many-to-many relationships. Overall, the document serves as a guide to basic ER modeling principles for conceptual database design.
Types Of Keys in DBMS
This document discusses different types of keys used in databases. It defines keys as attributes that uniquely identify rows in tables. It then explains various key types including primary keys, candidate keys, super keys, alternate keys, unique keys, composite keys, foreign keys, natural keys and surrogate keys. For each key type, it provides examples from sample tables and discusses their properties and how they differ from each other. The document concludes that databases generally only contain primary, foreign, unique and surrogate keys, while other key types are conceptual, and that each table requires a unique key to reliably access and identify data.
RDBMS
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RDBMS concepts
This document provides an introduction to relational database management systems (RDBMS). It discusses the key components and functions of an RDBMS including data storage and retrieval, transaction support, concurrency control, and authorization services. Various database concepts are explained such as the relational model, normalization forms, indexing techniques like B+ trees and hashing, and concurrency control methods like locking. Transaction properties like atomicity, consistency, isolation, and durability are also covered. Join operations and views are defined. The document provides a high-level overview of fundamental RDBMS concepts.
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The document discusses the entity-relationship (ER) model for database design. It describes the basic constructs of ER modeling including entities, attributes, relationships, and cardinality. Entities can have attributes and exist in entity sets. Relationships associate entities and have properties like degree, connectivity, and cardinality. The ER diagram uses graphical notation to represent these constructs including rectangles for entities and lines or diamonds for relationships. The document provides examples of modeling customers, loans, and university course enrollment using the ER model.
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Architecture of dbms(lecture 3)
This document describes the three level architecture of a database management system (DBMS): the external, conceptual, and internal levels. The external level defines different views of the database for users. The conceptual level defines the logical structure and relationships of the entire database. The internal level defines the physical storage and implementation of the data. The document also discusses logical and physical data independence, which refer to the ability to modify schemas at different levels without affecting higher levels.
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This document provides an overview of database concepts and terminology. It discusses different types of databases based on number of users (single, multi, workgroup, enterprise), number of computers used (centralized, distributed), and timeliness of data (production, data warehouse). It also covers database categorizations, the relational model, entity types and occurrences, relationship types and occurrences, attributes, keys, and E.F. Codd's 12 rules for relational databases. The document is intended as a reference for a database systems course.
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This document contains descriptions and figures related to entity-relationship diagrams (ERDs) and database schemas. There are over 15 labeled figures showing ERDs for different examples including information about people, brokerages, student registration systems, and more. The document uses these diagrams to illustrate ERD concepts and how they can be translated into database schemas and relations.
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Here are the entity relationship diagrams and tables for the car insurance company database:
(a) E-R Diagram:
Person - owns - Car
(1:M)
Car - involved in - Accident
(0:M)
(b) Tables:
person
(driver_id primary key,
name, address)
car
(license primary key,
year, model, driver_id foreign key references person)
accident
(report_number primary key,
date, location)
participated
(driver_id foreign key references person,
license foreign key references car,
report_number foreign key references accident
Er to tables
The document discusses the process of logical database design, which involves converting conceptual models represented by entity-relationship (ER) diagrams into relational database tables. It describes how different types of relationships in ER diagrams, such as one-to-one, one-to-many, and many-to-many, translate to tables and foreign keys. The document also introduces data normalization as a process for structuring tables to eliminate redundancy among non-key attributes and provides examples of designing databases for different domains.
Database language
This document discusses database languages used in database management systems (DBMS). It describes three types of database languages: data definition language (DDL) used to define and modify the database schema; data manipulation language (DML) used to insert, update, delete and retrieve data; and data control language (DCL) used to control access privileges. Examples are provided for common statements in each language type like CREATE, ALTER, DROP for DDL and INSERT, UPDATE, DELETE, SELECT for DML. Case sensitivity and data types are also briefly covered.
FUNCTION DEPENDENCY AND TYPES & EXAMPLE
Functional dependency defines a relationship between attributes in a table where a set of attributes determine another attribute. There are different types of functional dependencies including trivial, non-trivial, multivalued, and transitive. An example given is a student table with attributes Stu_Id, Stu_Name, Stu_Age which has the functional dependency of Stu_Id->Stu_Name since the student ID uniquely identifies the student name.
Entity relationship modelling
This document provides an overview of entity-relationship modeling as a first step for designing a relational database. It describes how to model entities, attributes, relationships, and participation constraints. Key aspects covered include using boxes to represent entity types, diamonds for relationship types, and labeling relationships with degrees. The document also discusses handling multi-valued attributes and deciding whether to model concepts as attributes or entity types.
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The document discusses the entity-relationship (E-R) data model. It defines key concepts in E-R modeling including entities, attributes, entity sets, relationships, and relationship sets. It describes different types of attributes and relationships. It also explains how to represent E-R diagrams visually using symbols like rectangles, diamonds, and lines to depict entities, relationships, keys, and cardinalities. Primary keys, foreign keys, and weak entities are also covered.
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The document discusses database management systems and their advantages over traditional file systems. It covers key concepts such as:
1) Databases organize data into tables with rows and columns to allow for easier querying and manipulation of data compared to file systems which store data in unstructured files.
2) Database management systems employ concepts like normalization, transactions, concurrency and security to maintain data integrity and consistency when multiple users are accessing the data simultaneously.
3) The logical design of a database is represented by its schema, while a database instance refers to the current state of the data stored in the database tables at a given time.
Relational algebra
The document discusses the topics covered in a database technologies course, including relational algebra operations. It provides examples and explanations of relational algebra concepts like selection, projection, join, union, difference, and cartesian product. It also discusses limitations of relational algebra in expressing complex queries involving transitive closure. The document contains practice questions related to relational algebra operations at the end.
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RDBMS
This document provides an overview of relational database management systems (RDBMS). It defines RDBMS as a system that structures data into tables with rows and columns, and can relate these tables through common fields. The key aspects covered include relational algebra operations like select, project, join; structured query language (SQL) for manipulating and retrieving data; and the advantages of RDBMS like supporting a tabular data structure, multi-user access, and imposing integrity constraints.
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This document provides an introduction to relational database management systems (RDBMS). It discusses the key components and functions of an RDBMS including data storage and retrieval, transaction support, concurrency control, and authorization services. Various database concepts are explained such as the relational model, normalization forms, indexing techniques like B+ trees and hashing, and concurrency control methods like locking. Transaction properties like atomicity, consistency, isolation, and durability are also covered. Join operations and views are defined. The document provides a high-level overview of fundamental RDBMS concepts.
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ER DIAGRAM TO RELATIONAL SCHEMA MAPPING
1) Entity types from ER diagrams are converted to tables, with attributes becoming columns and the entity's key becoming the primary key. Multi-valued attributes become separate tables linked by foreign keys.
2) Weak entities become tables with a composite primary key of the strong entity's primary key and the weak entity's key.
3) Relationships are represented by either adding foreign keys between tables or creating a separate table for many-to-many relationships containing foreign keys from the related tables.
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Unit 2 DBMS
The document discusses database design concepts including the entity-relationship model, normalization, and functional dependencies. It provides descriptions of key concepts such as entities, attributes, relationships, and mapping approaches from ER diagrams to relational schemas. It also covers normal forms up to BCNF and the goals of normalization to reduce data redundancy and anomalies.
database.pptx
An entity-relationship diagram (ERD) is a data modeling technique used to graphically represent the relationships between entities in a database. The key components of an ERD include entities, attributes, and relationships. Entities represent real-world objects, attributes describe entities, and relationships define interactions between entities. To create an ERD, the first steps are identifying entities, determining relationships between entities, analyzing relationship cardinality, and drawing the diagram. The ERD can then be converted to a relational database by creating tables for each entity and relationship with columns for each attribute.
Advantages and disadvantages of er model in DBMS. Types of database models ..
Types of database models
Hierarchical database model.
Relational model.
Network model.
Object-oriented database model.
Entity-relationship model.
Document model.
Entity-attribute-value model.
Star schema.
Use analyzed requirements in the design of database.pptx
An entity-relationship (ER) diagram is used to design relational databases by modeling the structure and relationships of entities in the database. An ER diagram represents entities as nouns and relationships as verbs using graphical symbols like rectangles, diamonds, and lines. It is an important tool for database design, troubleshooting, and analysis across fields like software engineering, business, education, and research. The key components of an ER diagram include entities, attributes, relationships, keys, and cardinality.
dbms mannual.pdf
ER diagrams are used to visually represent the logical structure of databases and the relationships between entities stored in a database. The key components of an ER diagram include entities represented by rectangles, attributes represented by ovals, and relationships represented by diamonds. ER diagrams help identify the entities, attributes, relationships, and cardinalities that should exist in a database design. Creating an ER diagram is an important first step before implementing a relational database.
Entity Relationship Diagram – ER Diagram in DBMS.pptx
An Entity-Relationship (ER) diagram is a design or blueprint of a database that describes the structure of a database using a diagram. The main components of an ER diagram are entities, attributes, and relationships. An ER diagram shows the relationships among entity sets where an entity set is a group of similar entities that can have attributes. The diagram represents the complete logical structure of a database.
Lecture one db
This document provides an overview of entity-relationship (ER) modeling concepts for conceptual database design. It defines entities as objects with attributes, and relationships as connections between entities. Entities can have simple or composite attributes. Relationships have names, participating entity sets, degrees, and mapping cardinalities like one-to-one, one-to-many, and many-to-many. ER diagrams use shapes and lines to represent these components and show cardinalities. The document also discusses recursive relationships, participation constraints, and examples of an ER diagram for products and suppliers.
1 - Database Management System.pdf
The document discusses database management systems (DBMS) and the entity-relationship (ER) model. It defines a DBMS as software that organizes, stores, and retrieves data from a database. The main elements of a DBMS are the physical database, database engine, and data scheme. An ER model uses diagrams to represent entities, attributes, and relationships within a database. Entities are objects with attributes and relationships, attributes describe entity properties, and relationships can be one-to-one, one-to-many, many-to-one, or many-to-many.
Er Modeling
Introduction of Database Design and Development,Logical Design and Conceptual Database Design,Data Retrival, Sql slides, Queries,Data Retrival, Sql slides, Queries,Er Model,Normalization etc
database
This presentation introduces database design using the entity-relationship model. It defines key concepts of the ER model including entities, attributes, relationships and cardinalities. It provides an example ER diagram and discusses extended features such as generalization, specialization and aggregation. The presentation was delivered to a professor by six students as part of their database management systems course.
Presentation of saad on e-r diagram.
The document presents an overview of entity-relationship (E-R) diagrams. It defines E-R diagrams as visual representations of entities and relationships within a system. The key components of E-R diagrams are described as entities, attributes, and relationships. Entities represent objects, attributes are properties of entities, and relationships show interactions between entities. The document also provides examples of different types of relationships, instructions for creating E-R diagrams, and applications of using E-R diagrams for database design and software engineering.
D I T211 Chapter 3
The document provides an overview of entity relationship modeling including:
1. The key elements of an ER model are entities, attributes, and relationships. Entities can have attributes and be connected by relationships.
2. An ER diagram graphically represents the ER model using symbols and connectors to show entities, attributes, and relationships between entities.
3. The document describes the different types of relationships and provides examples of how to construct ER diagrams.
Fundamentals of database system - Data Modeling Using the Entity-Relationshi...
Fundamentals of database system - Data Modeling Using the Entity-Relationshi...Mustafa Kamel Mohammadi
In this chapter you will learn
Relational data model concepts
What is entity?
What is attribute and it’s types
What is relationship?
What is an Entity-Relationship data model?
Relational data model constraints
Characteristics of relation
dbms
The document provides an overview of entity-relationship (ER) modeling concepts including:
- Entity sets represent collections of real-world objects or concepts that share common properties
- Relationship sets represent associations between entity sets
- ER diagrams use graphical symbols like rectangles, diamonds, and lines to represent entity sets, relationship sets, and attributes
- Mapping cardinalities define the number of entities in one set that can be associated with entities in another set through a relationship
- Keys uniquely identify entities and relationships and primary keys are selected from candidate keys
ER model
- The document discusses entity-relationship (E-R) modeling concepts including entity sets, relationship sets, attributes, keys, E-R diagrams, mapping cardinalities, and design issues when converting between binary and non-binary relationships.
- It provides examples of how to represent various relationship types like one-to-one, one-to-many, many-to-one, and many-to-many using E-R diagrams with lines and arrows to show cardinality constraints.
- Guidelines are given for choosing between entity sets vs attributes and relationship sets, and converting non-binary relationships to binary form while preserving semantics.
Er model
The document provides an overview of entity-relationship (ER) modeling concepts including:
- Entity sets and relationship sets which form the basic constructs of an ER model
- Attributes, keys, and cardinality constraints which provide further details on entities and relationships
- ER diagrams which visually depict the ER model through graphical symbols
- Additional ER modeling features such as weak entities, specialization, and aggregation
The document concludes by discussing how an ER schema can be reduced to tables to represent the data in a relational database.
DBMS - ER Model
The Entity-Relationship model is used for database design and includes several phases:
1) Requirement analysis involves understanding the data to be stored, applications needed, and common operations.
2) Conceptual design builds the ER model to describe data simply matching user requirements.
3) Logical design converts the ER model into a relational database schema.
4) Physical design addresses indexing, clustering, and security access rules.
Er model
The document discusses the Entity-Relationship (ER) model, which is a high-level data model used to define data elements and relationships for a specified system. The ER model develops a conceptual design for the database and provides a simple view of data. Key components of the ER model include entities, attributes, relationships, cardinality, and notations used in ER diagrams. Advantages of the ER model are that it is conceptually simple, provides better visual representation, acts as an effective communication tool, and can be easily converted to other data models like the relational model.
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Administrator of Online Examination has multiple features such as Add, Delete...
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Advantages and disadvantages of er model in DBMS. Types of database models ..
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Use analyzed requirements in the design of database.pptx
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Entity Relationship Diagram – ER Diagram in DBMS.pptx
Entity Relationship Diagram – ER Diagram in DBMS.pptx
Fundamentals of database system - Data Modeling Using the Entity-Relationshi...
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Entity relation(1)
- 1. History of ER (entity relationship) Diagram: Peter Chen developed ERDs in 1976. Since then Charles Bachman and James Martin have added some slight refinements to the basic ERD principles.
- 2. ER (entity relationship) Diagram: ER Model is represented by means of an ER diagram. Any object, for example, entities, attributes of an entity, relationship sets, and attributes of relationship sets, can be represented with the help of an ER diagram.
- 3. Why we design ER diagrams?
- 4. Why we design ER diagrams? The software developer/analyst or database designer/analyst gains a better understanding of the information to be contained in the database through the process of constructing the ERD. The ERD serves as a documenting tool.
- 5. ER (entity relationship) Diagram: There are three basic elements in ER-Diagrams: Entities are the "things" for which we want to store information. An entity is a person, place, thing or event. Attributes are the data we want to collect for an entity. Relationships describe the relations between the entities.
- 7. Entity Any object having attributes and their values from real word is entity. Entities are represented by means of rectangles. Rectangles are named with the entity set they represent.
- 8. How to represent Entity
- 9. 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.
- 10. How to represent Relationship
- 11. Attribute Attributes are the properties of entities. Attributes are represented by means of ellipses. Every ellipse represents one attribute and is directly connected to its entity (rectangle).
- 12. How to represent Attribute
- 13. Composite attributes If the attributes are composite, they are further divided in a tree like structure. Every node is then connected to its attribute. That is, composite attributes are represented by ellipses that are connected with an ellipse.
- 15. Derived attributes Derived attributes are depicted by dashed ellipse.
- 17. Multivalued attributes Multivalued are depicted by double ellipse.
- 19. Notations of ER diagram
- 20. One to One Relationship For example, if each customer in a database is associated with one mailing address.
- 21. One to One Relationship
- 22. One to many Relationship For example, a single customer might place an order for multiple products. The customer is associated with multiple entities, but all those entities have a single connection back to the same customer.
- 23. One to many Relationship
- 24. Many to many Relationship For example, at a company where all call center agents work with multiple customers, each agent is associated with multiple customers, and multiple customers might also be associated with multiple agents.
- 25. Many to many Relationship
- 26. The phase in which we need to design an ER diagram In Designing phase we need to design ERDs.
- 27. ER diagram of Internet Sales Model
- 28. Any Questions ??
- 29. Thank you for your attention!