Specialization Process Limitations in Databases
Specialization is a database design process where an entity type (superclass) is divided into more specialized entity types (subclasses) that share common attributes but also have unique ones. It's a top-down approach.
Analyzing Specialization Capabilities
Let's examine what specialization allows and does not allow:
- Defining Subclasses: Specialization allows the creation of a set of subclasses derived from a superclass. (Corresponds to Option 1)
- Adding Specific Attributes: It enables subclasses to have their own unique attributes that are not present in the superclass. (Corresponds to Option 2)
- Establishing Specific Relationships: Subclasses can participate in relationships distinct from the superclass or other subclasses. (Corresponds to Option 4)
The Operation Not Supported by Specialization
The core idea of specialization is to break down a general entity into specific ones. The reverse process, combining specific entities into a more general one, is called Generalization.
- Generalization Process: Defining a generalized entity type from given entity types is the definition of generalization, not specialization. Specialization moves from general to specific; it does not create a general type from specifics. (Corresponds to Option 3)
Identifying the Correct Answer
Therefore, the specialization process does not allow the defining of a generalized entity type from the given entity types.
Correct Answer: Option 3
Important Questions from ER Model
______ are some problems that can occur when creating an entity-relationship model.
The values of the attributes in a database describe a particular _______.
Which of the following data item is not broken down into smaller units is?
Which of the following statements is/are TRUE?
(i) A weak entity set is identified solely by its partial key (discriminator).
(ii) The identifying relationship type between a weak entity type and its owner entity type must have total participation from the weak entity type.
- Consider an ER model with the entities E1(A11, A12, A13) and E2(A21, A22, A23), where, A11, A12, A13 are the attributes of E1, and A21, A22, A23 are the attributes of E2. Let A22 be a multi-valued attribute. A11 and A21 are the primary keys of E1 and E2, respectively.
Let R12 be a many-to-many relationship between E1 and E2. Participation of both E1 and E2 in R12 is total.
The minimum number of relations required to convert the ER model into relational model (assuming there is no other functional dependency) where each relation is in third normal form (3NF) is __________ . (Answer in integer)
