This set of Oracle Database Multiple Choice Questions & Answers (MCQs) focuses on “Attribute, tuple and Entity”.
1. In an E-R diagram an entity set is represent by a
c) Diamond box
Explanation: Entity types represent sets of objects and are pictured by rectangular nodes.
2. A relational database developer refers to a record as
a) A criteria
b) A relation
c) A tuple
d) An attribute
Explanation: A tuple is analogous to a record in non-relational databases.
3. The relational model feature is that there
a) is no need for primary key data
b) is much more data independence than some other database models
c) are explicit relationships among records
d) are tables with many dimensions
Explanation: The relational model is the conceptual basis of relational databases. Proposed by E.F.Codd in 1969, it is a method of structuring data using relations, which are grid-like mathematical structures consisting of columns and rows.
4. E-R model uses this symbol to represent weak entity set ?
a) Dotted rectangle
c) Doubly outlined rectangle
d) None of the Mentioned
Explanation: A weak entity set is indicated by a doubly-outlined box.
5. Which of the following is record based logical model?
a) Network Model
b) Object oriented model
c) E-R Model
d) None of the Mentioned
Explanation: The network model is a database model conceived as a flexible way of representing objects and their relationships.
6. A ___________ normal form normalization will be needed where all attributes in a relation tuple are not functionally dependent only on the key attribute.
Explanation: A database is in third normal form if it satisfies the following conditions:1)It is in second normal form. 2)There is no transitive functional dependency
7. Identify the criteria for designing database from the point of view of user
a) No redundancy
b) No inapplicable attributes
c) Uniformity in naming & definitions of the data items
d) All of the Mentioned
Explanation: To designing database from the point of user view we need all the mentioned required.
8. The relational model is based on the concept that data is organized and stored in two-dimensional tables called _____________
Explanation: In the context of a relational database, a row also called a record or tuple represents a single, implicitly structured data item in a table.
9. An aggregation association is drawn using which symbol:
a) a line which loops back onto the same table
b) small closed diamond at the end of a line connecting two tables
c) small open diamond at the end of a line connecting two tables
d) small triangle at the end of a line connecting the aggregated item and multiple component items
Explanation: There are three primary inter-object relationships: association, aggregation, and composition. Using the right relationship line is important for placing implicit restrictions on the visibility and propagation of changes to the related classes, matter which play major role in reducing system complexity.
10. An n-array relationship is drawn using which symbol:
a) A diamond
b) A line with arrows showing direction
c) A line without arrows showing direction
d) A rectangle
Explanation: When a single parent-child relationship exists, the relationship is called binary. All of the previous examples of relationships to this point have been binary relationships. However, when creating a data model, it is not uncommon to come across n-array relationships, the modeling name for relationships between two or more parent entities and a single child table.
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