Which of the following provides the best description of an entity type?
2015
Which of the following provides the best description of an entity type?
- A.
A specific concrete object with a defined set of processes (e.g. Jatin with diabetes)
- B.
A value given to a particular attribute (e.g. height - 230 cm)
- C.
A thing that we wish to collect data about zero or more, possibly real world examples of it may exist
- D.
A template for a group of things with the same set of characteristics that may exist in the real world
Attempted by 1577 students.
Show answer & explanation
Correct answer: D
Answer: A template for a group of things with the same set of characteristics that may exist in the real world
Explanation: An entity type is a definition or schema that describes a class of real-world objects you want to store data about. It specifies the common attributes and structure shared by that class.
Entity type vs instance: The entity type is the template (for example, Patient). Individual real-world examples (for example, one specific patient) are instances of that entity type.
Attributes and attribute values: The entity type defines attributes (for example, height). Specific values (for example, 230 cm) are attribute values for an instance.
Zero or more instances: A well-defined entity type may have zero, one, or many real-world instances; the type itself is the abstract template.
Quick examples to make the differences clear:
Entity type: Patient → attributes: name, date of birth, height
Instance: A particular person with diabetes (this is an example of the Patient entity type)
Attribute value: height = 230 cm (a value for the height attribute of an instance)