Multiple choice questions 20 in DBMS

General Quiz in DBMS

1. A mathematical definition of a relationship (as in an E/R model) is: if A and B are sets, then a relationship R is a subset of the set A U B.

TRUE
FALSE

2. There is no formal way to specify multiple keys in an E/R diagram.

TRUE
FALSE

3. A "weak entity set" is not an entity set, it is a special type of relationship between two entity sets.

TRUE
FALSE

4. Let's say you examined all the tuples in a relation at a particular time, and found that no two tuples have the same value for a particular attribute A. You can designate A to be a key for the relation.

TRUE
FALSE

5. SQL allows you to not only create a new table, but also to delete an existing table from the database.

TRUE
FALSE

6. In translating subclass entity sets into the relational model, the "use nulls approach" creates the fewest relations.

TRUE
FALSE

7. In relational algebra, the schema of R1 - R2 includes the attributes of R1 that are not attributes of R2.

TRUE
FALSE

8. A Theta-join is a Cartesian product operation followed by a projection operation.

TRUE
FALSE

9. Schema refinement using the 3rd Normal Form is lossless (avoids information loss).

TRUE
FALSE

10. A clustered index is one where each data record has an entry in the index, while in an unclustered index, only some records have an entry.

TRUE
FALSE

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Correct answers:

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