binary relationship -An ER term for an association (relationship) between two entities. For
example, PROFESSOR teaches CLASS.
cardinality -An attribute that can be further subdivided to yield additional attributes. For
example, a phone number such as may be divided into an area code (615), an
...
binary relationship -✔✔An ER term for an association (relationship) between two entities. For
example, PROFESSOR teaches CLASS.
cardinality -✔✔An attribute that can be further subdivided to yield additional attributes. For
example, a phone number such as 615-898-2368 may be divided into an area code (615), an
exchange number (898), and a four-digit code (2368). Compare to simple attribute.
composite identifier -✔✔In ER modeling, a key composed of more than one attribute.
derived attribute -✔✔An attribute that does not physically exist within the entity and is derived via
an algorithm. For example, the Age attribute might be derived by subtracting the birth date from the
current date.
existence-dependent -✔✔A property of an entity whose existence depends on one or more other
entities. In such an environment, the existence-independent table must be created and loaded first
because the existence-dependent key cannot reference a table that does not yet exist.
existence-independent -✔✔A property of an entity that can exist apart from one or more related
entities. Such a table must be created first when referencing an existence-dependent table.
identifiers -✔✔One or more attributes that uniquely identify each entity instance.
iterative process -✔✔A process based on repetition of steps and procedures.
mandatory participation -✔✔A relationship in which one entity occurrence must have a
corresponding occurrence in another entity. For example, an EMPLOYEE works in a DIVISION. (A
person cannot be an employee without being assigned to a company's division.)
multivalued attributes -✔✔An attribute that can have many values for a single entity occurrence. For
example, an EMP_DEGREE attribute might store the string "BBA, MBA, PHD" to indicate three
different degrees held.
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