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A relationship describes an association among two or more entities, usually represented by a diamond shape.

An Entity-Relationship diagram is a visual representation of entities, attributes, and relationships between them in a database.

An attribute is a property or characteristic of an entity or relationship. Each attribute has a domain of values it can take.

A composite key is formed by combining two or more attributes to uniquely identify an entity instance when a single attribute is not sufficient.

An entity represents a real-world object or concept with a unique existence in the database. It is depicted as a rectangle in ER diagrams.

Cardinality defines the number of instances of one entity that can or must be associated with each instance of another entity.

A derived attribute is not stored in the database but can be calculated or derived from other stored attributes.

Participating entities refer to the distinct entities that are involved in a relationship.

This specifies whether all instances of an entity are required to participate in a relationship (total participation) or not (partial participation).

A multivalued attribute can have multiple values for a single entity instance. They are typically depicted by a double oval in ER diagrams.

A composite attribute is an attribute that can be divided into smaller sub-parts, which represent more basic attributes with independent meanings.

A primary key is an attribute or a set of attributes that uniquely identifies an entity instance in an entity set.

A weak entity cannot be uniquely identified by its own attributes alone and relies on a 'part-of' relationship with another entity.

An identifier is any attribute or combination of attributes that uniquely identifies an entity instance within an entity set.