1
GATE CSE 2009
MCQ (Single Correct Answer)
+2
-0.6
Consider the following relational schema:

Suppliers(sid : integer, sname : string, city : string, street : string)

Parts(pid : integer, pname : string, color : string)

Catalog(sid : integer, pid : integer, cost : real)

Consider the following relational query on the above database:
SELECT S.sname 
FROM Suppliers S 
WHERE S.sid NOT IN 
     (SELECT C.sid 
      FROM Catalog C 
      WHERE C.pid NOT IN 
        (SELECT P.pid 
         FROM Parts P 
         WHERE P.color<> 'blue'))
Assume that relations corresponding to the above schema are not empty. Which one of the following is the correct interpretation of the above query?
A
Find the names of all suppliers who have supplied a non-blue part.
B
Find the names of all suppliers who have not supplied a non-blue part.
C
Find the names of all suppliers who have supplied only blue parts.
D
Find the names of all suppliers who have not supplied only blue parts.
2
GATE CSE 2009
MCQ (Single Correct Answer)
+2
-0.6
Consider the following relational schema:

Suppliers(sid : integer, sname : string, city : string, street : string)

Parts(pid : integer, pname : string, color : string)

Catalog(sid : integer, pid : integer, cost : real)

Assume that, in the suppliers relation above, each supplier and each street within a city has a unique name, and (sname, city) forms a candidate key. No other functional dependencies are implied other than those implied by primary and candidate keys. Which one of the following is TRUE about the above schema?
A
The schema is in BCNF
B
The schema is in 3NF but not in BCNF
C
The schema is in 2NF but not in 3NF
D
The schema is not in 2NF
3
GATE CSE 2009
MCQ (Single Correct Answer)
+2
-0.6
Consider two transactions T1 and T2 and four schedules S1, S2, S3, S4 of T1 and T2 as given below:

T1: R1[ x ] W1[ x ] W1[ y ]
T2: R2[ x ] R2[ y ] W2[ y ]
S1: R1[ x ] R2[ x ] R2[ y ] W1[ x ] W1[ y ] W2[ y ]
S2: R1[ x ] R2[ x ] R2[ y ] W1[ x ] W2[ y ] W1[ y ]
S3: R1[ x ] W1[ x ] R2[ x ] W1[ y ] R2[ y ] W2[ y ]
S4: R2[ x ] R2[ y ] R1[ x ] W1[ x ] W1[ y ] W2[ y ]

Which of the above schedules are conflict-serializable?
A
S1 and S2
B
S2 and S3
C
S3 only
D
S4 only
4
GATE CSE 2009
MCQ (Single Correct Answer)
+2
-0.6
Let R and S be relational schemes such that R = { a, b, c } and S = { c }. Now consider the following queries on the database:

I. $$\pi_{R-S}(r) - \pi_{R-S} \left (\pi_{R-S} (r) \times s - \pi_{R-S,S}(r)\right )$$

II. $$\left\{t \mid t \in \pi_{R-S} (r) \wedge \forall u \in s \left(\exists v \in r \left(u = v[S] \wedge t = v\left[R-S\right]\right )\right )\right\}$$

III.$$\left\{t \mid t \in \pi_{R-S} (r) \wedge \forall v \in r \left(\exists u \in s \left(u = v[S] \wedge t = v\left[R-S\right]\right )\right ) \right\}$$

IV. Select R.a, R.b
    From R, S
    Where R.c = S.c
Which of the above queries are equivalent?
A
I and II
B
I and III
C
II and IV
D
III and IV
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Medical
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Graduate Aptitude Test in Engineering
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