Specialization Lattice stands for
An entity type can participate as a subclass in more than one specialization.
In the enhanced ER model, if every subclass takes part in only one specialization, the structure is a hierarchy (tree).
When a subclass can take part as a subclass in more than one specialization, i.e. it may have several superclasses, the structure becomes a specialization lattice and the subclass is a shared subclass.
So a lattice is defined by participation in more than one specialization.
Hence, An entity type can participate as a subclass in more than one specialization.
Similar Questions
What kind of mechanism is to be taken into account for converting a weak entity set into strong entity set in entity-relationship diagram ?
Which of the following provides the best description of an entity type ?
Let \(E_{1}\) and \(E_{2}\) be two entities in E-R diagram with simple single valued attributes. \(R_{1}\) and \(R_{2}\) are two relationships between \(E_{1}\) and \(E_{2}\) where \(R_{1}\) is one - many and \(R_{2}\) is many - many. \(R_{1}\) and \(R_{2}\) do not have any attribute of their own. How many minimum number of tables are required to represent this situation in the Relational Model ?
Which of the following statements is FALSE about weak entity set ?
For a weak entity set to be meaningful, it must be associated with another entity set in combination with some of their attribute values, is called as :
Let pk(R) denotes primary key of relation R. A many-to-one relationship that exists between two relations R1 and R2 can be expressed as follows :
Important Questions from ER Model
- 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) - Specialization process does not allow
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.
