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INTRO. TO DATABASE MGMT. SYST.
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Consider a relation R(A, B, C, D, E, F) with the following functional dependencies: 1. A → BC 2. C → D 3. B → E 4. E → F
Using the attribute closure method, is A → F derivable from the given FDs?
Consider a relation R(P, Q, R, S, T) with functional dependencies: 1. PQ → R 2. R → S 3. S → T
R is decomposed into R1(P, Q, R) and R2(R, S, T).
Is this decomposition dependency preserving?
Which of the following is true about an entity in an ER model?
What is a weak entity?
Suppose we have the following schema:
,
,
describing, respectively, people, types of cars, and cars and their owners. The data corresponding to these tables is as follows:
| ID | NAME |
| 1 | Madeleine |
| 2 | Alice |
| 3 | Nalini |
| CarTypeId | Type |
| 1 | Small |
| 2 | Medium |
| 3 | Large |
| CarId | OwnerId | CarTypeId | CarName |
| 1 | 1 | 1 | Nano |
| 2 | 2 | 2 | Santro |
Select the correct returned tuple of the following SQL query:
select distinct Q.name from (select P.name, C.carName, CT.carTypeId from Person P left outer join Car C on (C.ownerId = P.id) inner join CarType CT on (C.carTypeId = CT.carTypeId)) as Q
Assuming set semantics, State true or false for the following statement:
The full outer-join operator ⟗ can be expressed as a combination of (⟕, ⟖, ∪).
Which of the following is NOT a type of attribute in an ER model?
What does cardinality in an ER model define?
Assuming set semantics, State true or false for the following statement:
The grouping operator 𝛾, can be expressed as a combination of (σ, Π, ∪).
Consider the following university database schema:
Student (SID, Name, Age, Major, GPA)
Course (CID, Title, Department, Credits)
Enrollment (SID, CID, Semester, Grade)
Professor (PID, Name, Department, Salary)
Teaches (PID, CID, Semester)
Which of the following relational algebra expression(s) will Find courses that are either taught by Professor A or taken by Student X but not both? (Note: there can be more than expressions)