ERD Symbols and Meanings

Design elements Crow’s Foot notation

Crow's Foot notation is used in Barker's Notation, Structured Systems Analysis and Design Method (SSADM), and information engineering. Crow's Foot diagrams represent entities as boxes, and relationships as lines between the boxes. Different shapes at the ends of these lines represent the cardinality of the relationship.

Entity-Relationship model making possibility to describe a database in which in the tables data can be the point to data in other tables - for instance, your entry in the database could point to several entries.

To create an ERD, software engineers mainly turn to dedicated drawing software, which contain the full notation resources for their specific database design - ERD symbols and meanings. CS Odessa has released an all-inclusive Entity-Relationship Diagram (ERD) solution for their powerful drawing program, ConceptDraw PRO.

Entity Relationship Diagram Symbols and Meaning - crow's foot notation

Example 1. Entity Relationship Diagram symbols and meaning (Mac OS X and Windows)

When you need to describe efficiently a database using the Crow’s Foot notation icons, ConceptDraw PRO gives you the ability to draw Entity Relationship diagram (ERD) fast and easy.

Design elements Chen's notation

The Chen's ERD notation is still used and is considered to present a more detailed way of representing entities and relationships.

Use also ConceptDraw PRO enhanced with powerful Entity-Relationship Diagram (ERD) solution to draw your own ER diagrams using Chen's notation icons.

Symbol Shape Name Symbol Description
ERD Symbols and Meaning - Entity Entity An entity is represented by a rectangle which contains the entity’s name.
ERD Symbols and Meaning - Weak Entity Weak Entity An entity that cannot be uniquely identified by its attributes alone. The existence of a weak entity is dependent upon another entity called the owner entity. The weak entity’s identifier is a combination of the identifier of the owner entity and the partial key of the weak entity.
ERD Symbols and Meaning - Associative Entity Associative Entity An entity used in a many-to-many relationship (represents an extra table). All relationships for the associative entity should be many
ERD Symbols and Meaning - Attribute Attribute In the Chen notation, each attribute is represented by an oval containing atributte’s name
ERD Symbols and Meaning - Key attribute Key attribute An attribute that uniquely identifies a particular entity. The name of a key attribute is underscored.
ERD Symbols and Meaning - Multivalue attribute Multivalued attribute An attribute that can have many values (there are many distinct values entered for it in the same column of the table). Multivalued attribute is depicted by a dual oval.
ERD Symbols and Meaning - Derived attribute Derived attribute An attribute whose value is calculated (derived) from other attributes. The derived attribute may or may not be physically stored in the database. In the Chen notation, this attribute is represented by dashed oval.
ERD Symbols and Meaning - Relationship Strong relationship A relationship where entity is existence-independent of other entities, and PK of Child doesn’t contain PK component of Parent Entity. A strong relationship is represented by a single rhombus
ERD Symbols and Meaning - Identifying Relationship Weak (identifying) relationship A relationship where Child entity is existence-dependent on parent, and PK of Child Entity contains PK component of Parent Entity. This relationship is represented by a double rhombus.

In addition to the vector stencil image libraries with full standardized Chen and Crow’s foot notations included, the Entity-Relationship Diagram (ERD) solution contains a number of ERD templates and samples added to the solution pack. They will help users quick start representing their own ideas.

Entity Relationship Diagram samples and templates in ConceptDraw STORE

Example 2. Entity Relationship Diagram samples and templates in ConceptDraw STORE

The following features make ConceptDraw PRO the best Entity Relationship Diagram ERD Software:

  1. You don't need to be an artist to draw professional looking diagrams in a few minutes.
  2. Large quantity of ready-to-use vector objects (entity relationship diagram symbols and meaning) makes your drawing diagrams quick and easy.
  3. Great number of predesigned templates and samples give you the good start for your own diagrams.
  4. ConceptDraw PRO provides you the possibility to use the grid, rules and guides. You can easily rotate, group, align, arrange the objects, use different fonts and colors to make your diagram exceptionally looking.
  5. All ConceptDraw PRO documents are vector graphic files and are available for reviewing, modifying, and converting to a variety of formats: image, HTML, PDF file, MS PowerPoint Presentation, Adobe Flash, MS Visio.
  6. Using ConceptDraw STORE you can navigate through ConceptDraw Solution Park, managing downloads and updates. You can access libraries, templates and samples directly from the ConceptDraw STORE.
  7. If you have any questions, our free of charge support is always ready to come to your aid.

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Entity Relationship Diagram Symbols

When we start to speak about databases, we must always mention database structure visualization. One of the most common ways to do it is to create an entity relationship diagram, and to put appropriate symbols on it. It is important either for database projecting and for its' future maintenance. Entity Relationship Diagram describes data elements and their relationships within a database. There are a set of special symbols that depict each element of an entity relationship diagram. Entities - represents some stable components such as supplier, employee, invoice, client, etc. Relation symbols show how the entities interact. Attributes define characteristics of the relationships. Attributes can be one-to-one or many-to-many. Physical symbols is used in the physical models. They represent items such as fields, tables, types and keys. ERD physical symbols are the building material for the database. Notation lines are used to illustrate the relationships. The most common method is Crow’s Feet notation. You can use ConceptDraw Entity-Relationship Diagram (ERD) solution to represent a database using the Entity-Relationship model.Entity Relationship Diagram Symbols
Picture: Entity Relationship Diagram Symbols
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Components of ER Diagram

It is easy to recreate any informational system structure using diagrams. There are three main components of any ER diagram: entity, attribute and relationship. Basing on these three components, one can define other, less used elements, such as weak entity or relationship, derived attribute, recursive relationship etc. This is the set of graphic elements of ERD Chen's notation. This ERD notation is used to represent an entity–relationship models. It involves the set of geometric forms: rectangles - depicting entities, ovals - representing attributes and diamonds depicting relationships assigned for first-class objects, that can have relationships and attributes of their own. Connections are displayed with arrowed lines. It is known that the Chen's ERD notation is used to show a detailed view of entities and relationships. ConceptDraw Entity-Relationship Diagram solution from the Software Development section of Solution Park provides the ability to create ERD of database structure for software development purposes using the Chen’s notation elements.Components of ER Diagram
Picture: Components of ER Diagram
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What is Entity-Relationship Diagram

Entity Relationship Diagram (ERD) is an acknowledged method to visualize the logical structure of databases. Using special symbols described in ERD notations you can depict a database of any complexity. The vector graphic ER diagrams produced when using ConceptDraw ERD solution can be used in whitepapers, presentations, datasheets, posters, or any technical materials.What is Entity-Relationship Diagram
Picture: What is Entity-Relationship Diagram
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Entity Relationship Diagram - ERD - Software for Design Crows Foot ER Diagrams

There are many ways to describe a database structure. One of the most usual is to draw an entity relationship diagram (ERD) using a Crow’s Foot notation to represent database elements. If you don’t want to draw it on paper, you should use an appropriate software. An entity-relationship (ER) diagram is used to show the structure of a business database. ERD represents data as objects (entities) that are connected with standard relationships symbols which Illustrate an association between entities. ERD, there is a wide range of ERD notations used by data bases architects for reflecting the relationships between the data entities. According to the crow’s foot notation relationships are drawn as single labeled lines designating a certain kinds of relationship. Crow foot notation is a most frequently used ERD standard, because of improved readability of diagrams, with a more accurate use of space on the page.Entity Relationship Diagram Software, Design Elements - Crows Foot (Windows, Macintosh)
Picture: Entity Relationship Diagram - ERD - Software for Design Crows Foot ER Diagrams
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Basic Flowchart Symbols and Meaning

While creating flowcharts and process flow diagrams, you should use special objects to define different statements, so anyone aware of flowcharts can get your scheme right. There is a short and an extended list of basic flowchart symbols and their meaning. Basic flowchart symbols include terminator objects, rectangles for describing steps of a process, diamonds representing appearing conditions and questions and parallelograms to show incoming data. This diagram gives a general review of the standard symbols that are used when creating flowcharts and process flow diagrams. The practice of using a set of standard flowchart symbols was admitted in order to make flowcharts and other process flow diagrams created by any person properly understandable by other people. The flowchart symbols depict different kinds of actions and phases in a process. The sequence of the actions, and the relationships between them are shown by special lines and arrows. There are a large number of flowchart symbols. Which of them can be used in the particular diagram depends on its type. For instance, some symbols used in data flow diagrams usually are not used in the process flowcharts. Business process system use exactly these flowchart symbols.Flowchart Symbols and Meaning, workflow diagram symbols, process flow diagram symbols
Picture: Basic Flowchart Symbols and Meaning
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Database Design

ConceptDraw PRO extended with IDEF Business Process Diagrams solution from the Business Processes area of ConceptDraw Solution Park is an ideal software for effective database design and drawing IDEF diagrams visually representing all steps of database design process.Database Design
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ConceptDraw PRO Database Modeling Software

ConceptDraw PRO is a very easy-to-use and intuitive database design tool which can save you hundreds of work hours. See database diagram samples created with ConceptDraw PRO database modeling database diagram software.Database model layout
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Draw Network Diagram based on Templates and Examples

ConceptDraw is rapid and powerful network diagram drawing software with rich examples, templates, design objects and stencils.Network diagram template - Common network topologies
Picture: Draw Network Diagram based on Templates and Examples

Basic Diagramming

Create flowcharts, organizational charts, bar charts, line graphs, and more with ConceptDraw PRO.Line chart - US population growth
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Bus Network Topology

If you have a small budget to design a computer network, you have to be very careful. One of the most cheap technologies to implement is a bus network topology, however it has many disadvantages. For instance, if the network cable is somehow damaged, the entire network won't work. This diagram illustrates a so-called "Bus" network topology. This type of network arrangement means that each computer or other device is linked to a main link (bus). The end nodes are shown as a circle. The links to the bus are depicted as solid vertical lines. The bus is shown as a bold horizontal line. This diagram can serve as a template for creating logical or physical network diagrams. The set of vector libraries supplied with ConceptDraw Computer and Networks solution contains the symbols of all LAN and WLAN elements required for creating network diagrams of any configuration.Bus Network Topology
Picture: Bus Network Topology
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