is a set of meaningful associations among entity types

is a group of objects with the same properties, which are identified by the enterprise as having an independent existence

property or characteristic of an entity type (often corresponds to a field in a table)

–link between entities (corresponds to primary key-foreign key equivalencies in related tables)

Ellipses

Diamonds: entity sets

A definable thing—such as a person, object, concept or event—that can have data stored about it.

Think of entities as .........

can be defined solely by its own attributes.

An entity set that do not have sufficient attributes to form a primary key

An entity is considered ........ if its tables are existence dependent. That is it can not exist without relationship with another entity.

The primary key is indicated in the ER model by underlining the attribute

Primary key can have no value .

In the primary key Value should not change over time

Primary key Can be one or more attributes.

A .......... key is composed of two or more attributes, but it must be
minimal

A property or characteristic of an entity. Often shown as an oval or circle.

are those that consist of a hierarchy of attributes Sub-attributes spring from an attribute

More than one attribute value is denoted, such as multiple phone numbers for a person

Derived Attribute :Both multivalued and composite attribute

Attributed is calculated or otherwise derived from another attribute, such as age from a birthdate