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What are the entities and attributes.give one example?

Entities are one type of storage place where we can store information whereas attributes is the piece of information for that entity. Example : The book is the entity set. Title, price, author name all are the attributes of the book entity.

Difference between specialization and generalization?

As the name implies, Generalization is going general. For example if you have entities like Medical-student, Engineering - student, Architecture - student so on, you can generalize and create an entity called Student (higher level entity) so others will be sub entities (lower level entities) of Student entity. One thing to keep in mind is that, the generalized entity is the union of all the sub entities, in the sense it will contain everything that is in its sub entities. This is Bottom Up approach! Specialization is about going specifically. For a given entity you create sub entities. For example if Staff entity is there, you create Maintenance staff, IT staff, Executive staff so on. Here the higher level entity (Employee) is given and we create the lower level entities. However unlike in Generalized entity, the higher level entity is NOT union of its lower level entities. Sub entities here will use some things from its higher level entity plus things on its own. This means that there could be things that's in lower level entities but not in higher level entity.

What is the difference between associative entity and relationship with attribute?

A relationship with attributes should be an associative entity when: - All relationships for the associative entity should be many - The associative entity could have meaning independent of the other entities - The associative entity should have attribute(s), but it may or may not have an identifier - The associative entity may participate in other relationships other than the entities of the associated relationship - Ternary relationships should be converted to associative entities

What is week entity sets?

In a relational database, a weak entity is an entity that cannot be uniquely identified by its attributes alone; therefore, it must use a foreign key in conjunction with its attributes to create a primary key.Wikipedia

Difference between entity type and entity set?

lets understand them all: 1.An Entity is a real world "thing" which have independent existence. 2.Entity type is a category. 3.entity type is strictly calling, "an instance of entity type". 4.An entity type defines a collection of entities that have the same attributes. 5.Entity set : the collection of all entities of a particular entity type in the database at any point of time is called Entity set.

What is difference between object and entity?

A database object is represented as one of the following: database, schema, table, column, primary key, and foreign key A database Entity is: An entity is a thing or object of importance about which data must be captured. All things aren't entities - only those about which information should be captured. Information about an entity is captured in the form of attributes and/or relationships. If something is a candidate for being an entity and it has no attributes or relationships, it isn't an entity. Database entities appear in a data model as a box with a title. The title is the name of the entity.

Difference between entity attributes and relationship in entity relationship diagram?

differents between entity and attributes

Entity type vs entity instance?

Entity Type : A collection of entities that share common properties or characteristics. for example student is an entity type with common attributes such as student_ID , Name, Class etc. These characteristics are common to all students. Entity Instance: A single occurrence of a particular entity type is called entity instance..

What is the plural of entity?


What should be the erd for website design?

ERD is an Entity Relationship Diagram which is a graphical representation of database entities (tables, table columns, table definitions, attributes) and inter-relationships between these entities (how the tables are connected).

When do you have to use an intersection entity in database?

If you have a many-to-many relationship between two entities you create an intermediate entity between.Now, the relationship between the first entity and intersection entity is one-to-many, and the relationship between the second entity and intersection entity is one-to-many also.

Difference between an entity class and an entity instance?

"An entity is a person, place, event, or thing about which data is collected...An instance is an occurence of an entity." - Systems Analysis & Design (4th) - DennisAn example of this would be STUDENT as the entity while JACK SMITH is an instance of that entity.If an entity is an individual "person, place, event, or thing about which data is collected", then an entity is an instance. Linguistically, entity is just another word for a single thing ("The existence of a thing as contrasted with its attributes.", Merriam-Webster's On-line Dictionary). Entities that have the same attributes are grouped in what are best called entity classes (it doesn't make sense to refer to a collection of entities as an entity). Entity and entity class are data modeling terms. The corresponding object modeling terms are object and class, albeit that a class typically has operations, which are foreign to an entity class.

How to draw entity relationship diagram?

To draw a relationship diagram, start by placing relationship at the center of the paper. Connect entities to the relationship, and branch out with the different attributes.

What is strong entities vs weak entities?

The table that has primary key is strong entity and the table that has no primary key is weak entity

What is the difference between a required attributes and optional attributes?

strong entity : in this the attributes must have values for instance . weak entity : in this the attributes may or may not have values for instance .

Define key in dbms with example?

Supper Key- s a set of one or more attributes that taken collectively and allow us to identify entities with in entity set.

How is subtraction like adding?

Subtraction is nothing like addition. If you are talking about addition, it means that 1+1=2 - one entity + one entity = two entities. Entities=numbers. However, for subtraction it is the opposite. 1-1 = 0 - one entity eats/- one entity = zero entities. There are no other entities to eat except for itself. Thus when it eats itself, there are no more entities left.

Explain weak and strong entity?

A weak entity is an entity set that does not have sufficient attributes so that it can form a primary key. A weak entity is depicted by drawing double rectangle in entity relationship diagrams. While a strong entity is an entity set that have sufficient attributes so that it can form a primary key.

What is an entity-relationship diagram?

An entity relationship diagram (ERD) represents the entities, or groups of information, and their relationships maintained for a business. An entity relationship diagram represents the entities, or groups of information, and their relationships maintained for a business. An entity relationship diagram represents the entities, or groups of information, and their relationships maintained for a business.

What is the meaning of entity set?

entity set is term as a collection of logicaly related entities.

How does the dictionary define the term entities?

The dictionary defines the term entities as being of existence. An entity is something that exists, for example an apple is an entity. Synonyms for entity include thing, being, substance, and creature.

How do you create the registered trademark in HTML?

You use an HTML entity, "®" (without the quotes).See related link for all HTML entities.

Possessive form of the word entity?

Possessive: entity's Plural: entities Possessive plural: entities'

How can you determine whether an object is an entity or an attribute?

Information contributed by Ramona Maxwell:An entity is a primary object in your database design and an attribute would further describe that object. In human terms if you are the entity, your attributes might be height, age, hair color and so on. In a sales database 'customer' might be an entity whose attributes could include name, address or account number. Entities and or their attributes are mapped in terms of their relationship to one another when designing your database. Helpful information on Entity Relationship Modeling can be found at the following link:http:/enzperiodzwikipediazperiodzorg/wiki/Entityzhyphenzrelationship_model

What is entity and entity set in dbms?

entity is a thing in the real world with an independent existance. and entity set is collection or set all entities of a particular entity type at any point of time. take an example: a company have many employees ,and these employees are defined as entities(e1,e2,e3....) and all these entities having same attributes are defined under ENTITY TYPE employee.and set{e1,e2,.....} is called entity set. we can also understand this by an anology . entity type is like fruit which is a class .we havn't seen any "fruit"yet though we have seen instance of fruit like "apple ,banana,mango etc.hence.. fruit=entity type=EMPLOYEE apple=entity=e1 or e2 or e3 enity set= bucket of apple,banana ,mango etc={e1,e2......}