Entity vs. Attribute

Difference Between Entity and Attribute

The report of entity modeling (ERM) technology is widely used to model databases. The report of entity is putting the process of finding an abstract and conceptual data. One of the main building blocks of ERM is an entity. The entity represents a real world object or thing that may be all alone independently and can be uniquely identified. The properties containing these entities are called attributes. The ER diagrams are product report asking entity. ER diagrams are derived using entities, attributes and other symbols (such as reports).

What is an Entity?

An entity is something that can exist independently and can be uniquely identified. Specifically, an entity is often a class, group or class of similar objects. In most cases, an entity represents a real world object like a car or an employee. Entities can be thought of as nouns as well as the names that stand up for the description of the problem to be solved. Representation of entities is in relational databases in the form of tables. In general, each entity will map to exactly one table in the database. The individual rows in the tables correspond to the actual case of the object / thing represented by the entity. Consider the example of an employee database in a company. In this, each row represents employees’ individual records.

What does an attribute mean?

Properties of entities, in an entity-relationship modeling, are known as attributes. That is, the attributes represent sub information of the object represented by the entity. The attributes define the individual cases and help make the difference between each case by describing their characteristics. Remember that attributes must be atomic as they cannot be assessed in the game.

In case of relational databases, the entities are implemented in the form of tables and the columns represent the attributes of the entities. For example, in the Employee table, the columns as the department, rank and salary are examples of employee attributes. To distinguish between the individual cases of the entity, one or more attribute fields with unique values (for all cases) can be chosen as a key. For example, the attribute number of social assistance (which is unique for all employees) is often used as the primary key of a table of employees. Sometimes multiple attributes can make the primary key too.

What is the difference between an entity and an attribute?

In the report of entity posing, entities represent objects / things in the real world that can be identified as unique and independent, while the attributes are the properties of these entities.

In relational database, entities become tables (each row representing individual cases), while attributes become columns of the corresponding tables. Designing databases, it is common to have confusion about choosing an entity against an attribute to represent a subject of real word. In a case where the address of the employee represents another entity or an attribute (connected to the entity used by a report)? A general rule of thumb is’ if an employee has more than one address, then the address must be an entity (since attributes are not evaluated in game)’. Similarly, if the structure of the address is important to capture, then again the address should be an entity (since attributes are atomic).

 

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  • Mansoor A250

    The answer is well described as easy to understand its a good struggle. thanx