What is the difference between data model and an entity relationship diagram?

What is the difference between data model and an entity relationship diagram?

Data modeling is a technique to document a software system using diagrams and symbols. It is used to represent communication of data. The highest level of abstraction for the data model is called the Entity Relationship Diagram (ERD). It is a graphical representation of data requirements for a database.

What is logical data model with example?

For example, a simple logical data model for a retail company can organize all necessary facts by store, product, and time, which are three common business perspectives typically associated with a retail business. Logical data models are independent of a physical data storage device.

What is the difference between conceptual model and logical model?

A conceptual data model identifies the highest-level relationships between the different entities. A logical data model describes the data in as much detail as possible, without regard to how they will be physical implemented in the database.

Is an ERD a logical data model?

For example ‘many to many’ tables may exist in logical or physical data model but they are just shown as a relationship not a table in the conceptual data model. ERD is a logical model.

What is primary key in ER diagram?

The primary key is a candidate key that is selected by the database designer to be used as an identifying mechanism for the whole entity set. It must uniquely identify tuples in a table and not be null. The primary key is indicated in the ER model by underlining the attribute.

What are two components of a logical data model?

The components of a logical data model include Entities, Relationships, and Attributes. Each Entity represents a set of persons, things, or concepts about which the business needs information. Each Relationship represents an association between two entities.

What is logical data model diagram?

The logical data modeling process produces a diagram similar to the one shown in the following diagram: A logical data model represents the definition, characteristics, and relationships of data in a technical, conceptual, or business environment.

What is the difference between logical and physical models?

The logical model and the physical model are separate models. The logical model enables you to represent business information and define business rules. The physical model enables you to focus on the physical implementation of the model in a database.

Can an entity not have a primary key?

EF does not require a primary key on the database. If it did, you couldn’t bind entities to views. You can modify the SSDL (and the CSDL) to specify a unique field as your primary key.

What are the types of data models?

Types of data models

  • Conceptual data model. Conceptual data models are the most simple and abstract.
  • Physical data model.
  • Hierarchical data model.
  • Relational data model.
  • Entity-relationship (ER) data model.
  • Object-oriented data model.
  • Data modeling software makers.
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