is the top ER chart tool. Entity-relationship diagrams (ERD) are necessary to modeling something from simple to complex databases, but the shapes and notations used can be very confusing. This guide will aid you to come to be an expert in ER diagram notation, and you will certainly be fine on your method to model your very own database!

Conceptual Data Models create a wide view of what need to be consisted of in the model set. Theoretical ERDs have the right to be used as the structure for logical data models. Castle may likewise be supplied to form commonality relationships between ER models as a basis because that data design integration. All of the icons shown listed below are found in the UML entity Relationship and Entity partnership shape library the

You are watching: The associative entity is also known as a ____ entity.

ERD reality symbols

Entities room objects or ideas that represent important data. Reality are typically nouns such together product, customer, location, or promotion. There room three varieties of entities commonly used in entity partnership diagrams.

Entity SymbolNameDescription


Strong entity

These shapes are elevation from other entities, and also are often referred to as parent entities, since they will frequently have weak entities that count on them. Castle will also have a primary key, separating each event of the entity.


Weak entity

Weak entities rely on some various other entity type. They don't have primary keys, and have no meaning in the diagram there is no their parental entity.


Associative entityAssociative entities relate the instances of several entity types. They likewise contain attributes particular to the relationship in between those entity instances.

ERD connection symbols

Within entity-relationship diagrams, relationship are supplied to record the interaction between two entities. Relationships are usually verbs such together assign, associate, or monitor and provide useful information that might not it is in discerned with simply the reality types.

Relationship SymbolNameDescription



Weak relationship

Weak Relationships space connections between a weak entity and also its owner.

ERD attribute symbols

ERD qualities are features of the entity that aid users to much better understand the database. Attributes are included to incorporate details that the assorted entities that are highlighted in a conceptual ER diagram.

Attribute SymbolNameDescription


Attributes are characteristics of an entity, a many-to-many relationship, or a one-to-one relationship.

Derived attribute

Derived characteristics are characteristics whose value can be calculated from connected attribute values.

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Make one ERD

The physics data design is the many granular level the entity-relationship diagrams, and also represents the process of adding information come the database. Physics ER models show all table structures, including column name, pillar data type, pillar constraints, primary key, international key, and also relationships between tables.

As displayed below, tables room another method of representing entities. The crucial parts of Entity-relationship Tables are:


Fields stand for the portion of a table that develop the attributes of the entity. Attributes are commonly thought of together columns in the database that the ERD models.

In the image above, InterestRate and also LoanAmount are both qualities of the reality that are included as fields.


Keys space one way to categorize attributes. ER diagrams aid users to version their databases by using various tables the ensure that the database is organized, efficient, and fast. Keys are used to link various tables in a database come each other in the most efficient way possible.

Primary Keys

Primary tricks are one attribute or mix of attributes that uniquely identifies one and also only one instance of one entity.

Foreign Keys

Foreign tricks are created any time one attribute relates to one more entity in a one-to-one or one-to-many relationship.

Each car can just be sponsor by one bank, because of this the primary an essential BankId indigenous the financial institution table is used as the foreign an essential FinancedBy in the vehicle table. This BankID is able to be offered as the foreign crucial for lot of cars.


Types refer to the type of data in the matching field in a table. Varieties can also refer to reality types, which explain the composition of an entity; e.g., a book's entity types are author, title, and published date.

While crow's foot notation is frequently recognized as the most intuitive style, some use OMT, IDEF, Bachman, or UML notation, follow to their preferences. Crow's foot notation, however, has an intuitive graphics format, making it the desired ERD notation for Consider using one of our crow Foot ER diagram templates.

Cardinality and ordinality

Cardinality refers to the maximum number of times an circumstances in one entity can relate to instances of an additional entity. Ordinality, top top the various other hand, is the minimum number of times an instance in one entity can be associated with an instance in the associated entity.

Cardinality and also ordinality are shown by the styling that a line and its endpoint, follow to the liked notation style.

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Building an effective ER diagrams has never been so quick and also easy with Through every typical entity-relationship shape accessible on and all editing and enhancing taking location on the cloud, collaborating v co-workers, teammates, supervisors, and also professors is extremely easy.