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"An ER model is an abstract way of describing a database. In the case of a relational database, which stores data in tables, some of the data in these tables point to data in other tables - for instance, your entry in the database could point to several entries for each of the phone numbers that are yours. The ER model would say that you are an entity, and each phone number is an entity, and the relationship between you and the phone numbers is 'has a phone number'. Diagrams created to design these entities and relationships are called entity–relationship diagrams or ER diagrams.
Using the three schema approach to software engineering, there are three levels of ER models that may be developed. ...
Conceptual data model ... is the highest level ER model in that it contains the least granular detail but establishes the overall scope of what is to be included within the model set.
Logical ER model ... contains more detail than the conceptual ER model. In addition to master data entities, operational and transactional data entities are now defined.
The physical ER model is normally developed to be instantiated as a database. Therefore, each physical ER model must contain enough detail to produce a database and each physical ER model is technology dependent since each database management system is somewhat different.
Physical model ... is normally forward engineered to instantiate the structural metadata into a database management system as relational database objects such as database tables, database indexes such as unique key indexes, and database constraints such as a foreign key constraint or a commonality constraint." [Entity–relationship model. Wikipedia]
This crow's foot entity-relationship diagram (ERD) example "Educational data base" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park.
ERD
ERD, entity,

entity-relationship diagram, ER-diagram, database ERD Entity-Relationship Diagram (ERD)

entity-relationship diagram, ER-diagram, database ERD
An Entity-Relationship Diagram (ERD) is a visual presentation of entities and relationships. That type of diagrams is often used in the semi-structured or unstructured data in databases and information systems. At first glance ERD is similar to a flowch

Software Diagrams

Modern software development begins with designing different software diagrams and also uses a large amount of diagrams in project management and creation graphic documentation. Very popular diagrams that depict a work of applications in various cuts and notations, describe databases and prototype Graphical User Interfaces (GUIs). Software engineering specialists and software designers prefer to use special technical and business graphics tools and applications for easy creation diagrams. One of the most popular is ConceptDraw DIAGRAM diagramming and vector drawing software. ConceptDraw DIAGRAM offers the possibility of drawing with use of wide range of pre-drawn shapes and smart connectors, which allow to focus not on the process of drawing, but on the task's essence. It is a perfect application for design and document development, planning tasks, visualization of data, design the databases, object-oriented design, creation flowcharts of algorithms, modeling business processes, project management, automation of management and development processes, and for many other tasks.

Components of ER Diagram

Entity-Relationship model gives the possibility to visually describe a database using the components of ER Diagram, entity relationship stencils, relationship symbols, work flow shapes. ER-diagram lets represent the data or entities, attributes of these entities and relationships between them, using standardized Crow’s Foot notation icons or Chen’s notation icons. An entity is an object of the real world, it can exist independently and has the instances which differ in attribute values (properties). The attributes give an unambiguous (uniquely) identification for the instance and are called the primary key, this key can be composite and combine several attributes. ConceptDraw DIAGRAM is a professional software available with Entity-Relationship Diagram (ERD) solution from Software Development area that lets create ERDs for various database systems, using Crow’s Foot and Chen’s notations. It is invaluable tool for software engineers and developers, it supports ODBC-compatible databases (Oracle, MySQL, MS Access, MS SQL, InterBase, Firebird and others).

data flow diagram, DFD templates Data Flow Diagrams (DFD)

data flow diagram, DFD templates
Data Flow Diagrams solution extends ConceptDraw DIAGRAM software with templates, samples and libraries of vector stencils for drawing the data flow diagrams (DFD).

Applications

ConceptDraw DIAGRAM is a multipurpose software from ConceptDraw suite intended for diagramming, business and technical drawing, and visual documenting. You can reach a lot of practical benefits from the use of ConceptDraw DIAGRAM. The list of ConceptDraw DIAGRAM applications and versatile possibilities is extremely great. Among them network and system diagramming, business diagramming, Cisco network design, network visualization, software and database design, software development, business flowcharting, data flow design, databases modeling and visualization, business processes modeling, business drawing, technical drawing, GUI prototyping, Organizational charts construction, business processes fixing, web site planning and design, Internet solutions design, information architecture design, UML modeling, ER diagrams design, home and landscape design, and a lot of other applications. ConceptDraw DIAGRAM offers the users a beneficial collaboration, compatibility with MS Visio and many other popular programs, including other products from ConceptDraw suite.

Entity Relationship Diagram Examples

Creation of Entity-Relationship (ER) model is a visual representation the structure of a business database, where data equates to entities or objects, which are linked by defined relationships expressing dependencies and requirements. By the nature, the ER model is an abstract visualization, a first step in design process towards creating a logical and functional database. ConceptDraw DIAGRAM professional software gives the ability to effectively describe a database using the Entity-Relationship model. Included to ConceptDraw Solution Park, the Entity-Relationship Diagram (ERD) solution contains the set of predesigned vector icons advocated by Chen's and Crow’s Foot notations that both can be used for data modeling and describing a database. Entity-Relationship Diagram (ERD) solution includes also helpful templates and incredibly large collection of varied Entity Relationship Diagram examples and samples offered at ConceptDraw STORE. Each of them can be used to develop your own model of a database of arbitrary complexity.
How to Build an Entity Relationship Diagram (ERD)
How to Build an Entity Relationship Diagram (ERD)

DFD Flowchart Symbols

A Data Flow Diagram (DFD) is a graphical technique which allows effectively model and analyze the information processes and systems. The ability to fast and easy create the DFDs is made possible with Data Flow Diagrams solution from the Software Development area of ConceptDraw Solution Park. For designing the Data Flow Diagrams are used simple DFD flowchart symbols which are connected each other by arrows depicting the data flow from one step to another.

Software development with ConceptDraw DIAGRAM

Modern software development requires creation of large amount of graphic documentation, these are the diagrams describing the work of applications in various notations and cuts, also GUI design and documentation on project management. ConceptDraw DIAGRAM technical and business graphics application possesses powerful tools for software development and designing technical documentation for object-oriented projects. Solutions included to the Software Development area of ConceptDraw Solution Park provide the specialists with possibility easily and quickly create graphic documentation. They deliver effective help in drawing thanks to the included package of templates, samples, examples, and libraries with numerous ready-to-use vector objects that allow easily design class hierarchies, object hierarchies, visual object-oriented designs, flowcharts, GUI designs, database designs, visualize the data with use of the most popular notations, including the UML and Booch notations, easy manage the development projects, automate projection and development.

Cross-Functional Flowchart - The easiest way to draw crossfunctional

ConceptDraw DIAGRAM diagramming software provides vector shapes and connector tools for quick and easy drawing diagrams for business, technology, science and education. Use ConceptDraw DIAGRAM enhanced with solutions from ConceptDraw Solution Park to create diagrams to present and explain structures, process flows, logical relationships, networks, design schemes and other visually organized information and knowledge.