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WorksheetsChapt.4 - Advanced Data Modeling
Total questions: 15
Worksheet time: 7mins
The entity ___ contains common characteristics, and the entity ___ each contains its own unique characteristics.
instance, set
subtype, supertype
supertype, subtype
subclass, superclass
Two criteria help the designer determine when to use subtypes and supertypes.
[Tick all that applies]
some distinguishing characteristic(s)
No unique attributes
several common features
The attribute in the supertype entity that determines to which subtype the supertype occurrence is related.
The relationship between a superclass and any one of its subclasses is called
one-to-one
is-a
one-to-many
many-to-many
___constraint means that an entity can be a member of at most one of the subclasses of the specialization.
Complete
Partial
If every EMPLOYEE must be either an HOURLY_EMPLOYEE or a SALARIED_EMPLOYEE, then this is a ___ specialization of EMPLOYEE.
Total
Partial
Overlapping
Shared
Deleting an entity from a superclass implies that
Inserting an entity in a superclass of a total specialization implies that
The entity will also be inserted in at least one of the subclasses.
A specialization hierarchy has the constraint that
allows for multiple specializations at the same level
a subclass may have more than one parent
each subclass has only one parent
Entity clusters are used to
group entities based on their size.
group entities based on their location.
group entities based on their color.
group similar entities together based on their attributes or characteristics.
A system-assigned primary key, generally numeric and auto-incremented.
When implementing a 1:1 relationship, where should you place the foreign key if one side is mandatory and one side is optional?
___occurs when you have one entity in two 1:M relationships to other entities, and there is an association among the other entities that is not expressed in the model.
Redundant relationship
Time-variant trap
Fan trap
Many-to-one relationship
The main concern with redundant relationships is
how would you deal with time-variant data from a database design point of view?
Creating an entity that contains the new value, the date of the change, and any other time-relevant data.
Storing time-variant data as an entity cluster
