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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 → B 2. BC → D 3. D → E
Which of the following functional dependencies must also hold?
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?
What is a weak entity?
Which of the following is true about an entity in an ER model?
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 (⟕, ⟖, ∪).
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)
What does cardinality in an ER model define?
Which of the following is NOT a type of attribute in an ER model?