Databases
Question 1 |
Which one of the following pairs is correctly matched in the context of database design?
I-D, II-A, III-B, IV-C | |
I-D, II-C, III-B, IV-A | |
I-C, II-D, III-A, IV-B | |
I-C, II-A, III-D, IV-B |
Question 1 Explanation:
Specialization: Specialization is a top-down approach, means higher to lower. Result of taking a subset of a higher level entity set to from a lower level entity set.
Generalization: Generalization is a bottom-up approach, means lower to higher. Result of taking the union of two or more disjoint(lower-level) entity sets to produce higher-level entity set.
Aggregation: It is treated as higher level entity sets and can participate in relationships. Mapping cardinalities: Number of entities to which another entity can be associated via a relationship set. An abstraction in which relationship sets(along with their associated entity sets) are treated as higher level entity sets, and can participate in relationships.
Mapping cardinalities: Express the number of entities to which another entity can be associated via a relationship set.
Generalization: Generalization is a bottom-up approach, means lower to higher. Result of taking the union of two or more disjoint(lower-level) entity sets to produce higher-level entity set.
Aggregation: It is treated as higher level entity sets and can participate in relationships. Mapping cardinalities: Number of entities to which another entity can be associated via a relationship set. An abstraction in which relationship sets(along with their associated entity sets) are treated as higher level entity sets, and can participate in relationships.
Mapping cardinalities: Express the number of entities to which another entity can be associated via a relationship set.
Question 2 |
Which of the following is not a logical database structure?
Chain
| |
Network | |
Tree
| |
Relational |
Question 2 Explanation:
Chain is not a logical database structure.
There are 2 questions to complete.