Recent questions in Databases

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1

Gate: Normalization
Consider a relation $R (A, B, C, D, E, F, G, H) $ where each attribute is atomic, and following functional dependencies exist. Following relation is in $1 NF, $ I help me to decompose relation into $BCNF$ $CH\rightarrow G$ $A\rightarrow BC$ $B\rightarrow CFH$ $E \rightarrow A$ $F\rightarrow EG$

asked Feb 11 in Databases by anusuccess (7 points) | 36 views

+1 vote

1 answer

2

GATE2019-11
Consider the following two statements about database transaction schedules: Strict two-phase locking protocol generates conflict serializable schedules that are also recoverable. Timestamp-ordering concurrency control protocol with Thomas' Write Rule can generate view serializable schedules that are ... of the above statements is/are TRUE? I only II only Both I and II Neither I nor II

asked Feb 7 in Databases by Arjun Veteran (384k points) | 1.6k views

+1 vote

1 answer

3

GATE2019-14
Which one of the following statements is NOT correct about the B+ tree data structure used for creating an index of a relational database table? B+ Tree is a height-balanced tree Non-leaf nodes have pointers to data records Key values in each node are kept in sorted order Each leaf node has a pointer to the next leaf node

asked Feb 7 in Databases by Arjun Veteran (384k points) | 1.5k views

0 votes

1 answer

4

GATE2019-32
Let the set of functional dependencies $F=\{QR \rightarrow S, \: R \rightarrow P, \: S \rightarrow Q \}$ hold on a relation schema $X=(PQRS)$. $X$ is not in BCNF. Suppose $X$ is decomposed into two schemas $Y$ and $X$, where $Y=(PR)$ ... $Y$ and $Z$ is dependency preserving and lossless Which of the above statements is/are correct? Both I and II I only II only Neither I nor II

asked Feb 7 in Databases by Arjun Veteran (384k points) | 1.6k views

+1 vote

3 answers

5

GATE2019-51
A relational database contains two tables Student and Performance as shown below: Student Roll_no Student_name 1 Amit 2 Priya 3 Vinit 4 Rohan 5 Smita Performance Roll_no Subject_code marks 1 A 86 1 B 95 1 C 90 2 A 89 2 C 92 3 C 80 The primary key of ... Student S, Performance P WHERE P.Marks >84 GROUP BY S.Student_name; The number of rows returned by the above SQL query is ________

asked Feb 7 in Databases by Arjun Veteran (384k points) | 2.7k views

+2 votes

2 answers

6

GATE2019-55
Consider the following relations $P(X,Y,Z), Q(X,Y,T)$ and $R(Y,V)$. P X Y Z X1 Y1 Z1 X1 Y1 Z2 X2 Y2 Z2 X2 Y4 Z4 Q X Y T X2 Y1 2 X1 Y2 5 X1 Y1 6 X3 Y3 1 R Y V Y1 V1 Y3 V2 Y2 V3 Y2 V2 How many tuples will be returned by the following relational algebra query? $\Pi_x (\sigma_{P.Y=R.Y \wedge R.V=V2)} (P \times R)) – \Pi_x (\sigma_{Q.Y = R.Y \wedge Q.T>2)} (Q \times R))$ Answer: ________

asked Feb 7 in Databases by Arjun Veteran (384k points) | 2k views

0 votes

2 answers

7

GATE 2019
Is the given data correct? If yes then what is the answer to this query?

asked Feb 6 in Databases by rakeshcoresoft (227 points) | 753 views

0 votes

1 answer

8

GATE 2019
What are the answers for Relational Algebra and SQL query?

asked Feb 6 in Databases by rakeshcoresoft (227 points) | 352 views

+1 vote

2 answers

9

Gate19

asked Feb 4 in Databases by Manoj Kumar Pandey (107 points) | 305 views

+2 votes

1 answer

10

GATE2019
5 Q. Given Statement. I. Strict 2 – Phase lock protocol generate Conflict Serializable schedule that are also recoverable II. Time stamp – ordering concurrency control protocol with Thomas write rule can generate view serialized schedule that are not conflict serializable which are True? A. Only I B. Only II C. Both True D. Both are false

asked Feb 4 in Databases by xariniov9 (365 points) | 289 views

0 votes

2 answers

11

Gate 2019: B+ Tree
Which of the following is not correct about B + Tree, which is used for creating index of relational database table? (a) Key values in each node kept in sorted order (b) Leaf node pointer points to next node (c) B + tree is height balanced tree (d) Non-leaf node have pointers to data records

asked Feb 4 in Databases by HeartBleed (485 points) | 237 views

0 votes

1 answer

12

gate 2019
what about time ordering protocol?

asked Feb 4 in Databases by pream sagar Active (1.7k points) | 194 views

0 votes

1 answer

13

Gate cse 2019
What is the answer for SQL query in yesterday gate exam?

asked Feb 4 in Databases by Mounikap (227 points) | 2.1k views

0 votes

0 answers

14

B+ Tree Records

asked Feb 2 in Databases by Na462 Loyal (8.6k points) | 89 views

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0 answers

15

Fundamentals of Database Systems, Ramez Elmasri
In an ER diagram, whether we want to underline all candidate keys or only the primary key?

asked Jan 31 in Databases by SreelakshmyCUCEK (7 points) | 24 views

0 votes

1 answer

16

Dbms-One to one
If we have 1:1 cardinality with total participation on exactly 1 side how many tables we need for a good design.Is it 2 or 1?

asked Jan 31 in Databases by Aravind Adithya 1 (213 points) | 32 views

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0 answers

17

Made easy mock test 1 DBMS super keys
Consider the following relation R(A1, A2,...A15) with (A1,A2, ... A6) of relation R are simple candidate key. The number of possible superkey in relation R is_

asked Jan 30 in Databases by Ram Swaroop Active (2.2k points) | 88 views

0 votes

1 answer

18

ACE TEST SERIES
is there is easy way to find no of candidate key in these type of questions.

asked Jan 30 in Databases by iamdeepakji (227 points) | 106 views

0 votes

1 answer

19

Dbms recoverablity
Consider the following schedule R1(a) W1(a) R2(a) commit2 W1(a) commit1 Is this schedule recoverable.I feel it is recoverable even though there is a dirty read

asked Jan 30 in Databases by Aravind Adithya 1 (213 points) | 66 views

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1 answer

20

Can 2PL have Read Write conflict?
Can 2PL have Read Write conflict? Consider following schedule with two transaction T1 T2 L_S(A) Read(A) L_X(A)---------------------------is T2 allowed to acquire exclusive lock on A? Write(A) L_S(A) ----------------------------------------------T1 already has this lock Read(A) Commit RollBack Will this schedule allowed by 2PL

asked Jan 29 in Databases by mehul vaidya Active (3k points) | 26 views

0 votes

0 answers

21

made easy cbt 2

asked Jan 28 in Databases by singh chetan (39 points) | 67 views

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0 answers

22

#DBMS
What are the parameters or procedure to follow to find out minimum no. of tables for given ER Diagram type of questions?

asked Jan 28 in Databases by Reshu $ingh (329 points) | 50 views

0 votes

0 answers

23

made easy cbt2
consider the following relational schema R(A,B,C,D,E,F,G) AB->C,BC->A,AC->B,B->D,D->E how many minimum relations required to decompose R into BCNF which satisfy lossless and FDP decomposition? initially i got 4 relation as R1(A,B,C) R2(D,E) R3(B,D) R4(A,B,F,G) but in R1 and R2 there is no common attribute, hence it will not be lossless??am i correct

asked Jan 28 in Databases by Gate Fever Active (4.7k points) | 72 views

0 votes

2 answers

24

#MadeEasyTestSeries
S: If a relation R is in 3NF but not in BCNF then relation R must consist atleast 2 overlapped candidate keys. True/False

asked Jan 28 in Databases by Reshu $ingh (329 points) | 54 views

0 votes

0 answers

25

applied course
How to convert above E-R diagram to Relations? Sorry for adding image instead of typing..

asked Jan 27 in Databases by screddy1313 (401 points) | 40 views

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0 answers

26

Relational algebra and SQL
SQL Aggregation is possible by extended relational algebra operators? SQL grouping is possible in relational algebra. Relational algebra is equivalent to safe relational calculus expressions, then grouping and aggregation possible in tuple relational calculus ... calculus? What about ordering? Please explain how will we consider these questions from GATE point of view.

asked Jan 27 in Databases by Aman Janko (47 points) | 23 views

0 votes

0 answers

27

Made easy CBT2
$R_2(A)$W_1(B)$W_1(C)$R_3(B)$R_2(B)$R_1(A)$C_1$R_2(C)$C_2$W_3(A)$C_3$ Is this schedule allowed under 2PL? [closed]

asked Jan 26 in Databases by Chaitrasj Junior (893 points) | 40 views

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0 answers

28

MADE EASY FULL SYLLABUS TEST 2019
Find minimum number of tables needed? Answer : (3) Can anyone please explain the answer and how to approach such complex er diagrams?

asked Jan 26 in Databases by vk_9_1_9 (123 points) | 51 views

0 votes

0 answers

29

Dense Indexing

asked Jan 26 in Databases by Na462 Loyal (8.6k points) | 140 views

0 votes

2 answers

30

Virtual GATE 2019
Which of the following is/are true? I. Every strict schedule is cascadeless schedule and recoverable schedule II. Every cascadeless schedule is recoverable schedule III. Every cascading rollback schedule is recoverable schedule IV. Every cascading rollback schedule is strict schedule V. Every recoverable ... I, II, and IV only (C) II, III, IV, and V only (D) I, II, and III only

asked Jan 26 in Databases by jatin khachane 1 Loyal (6.4k points) | 107 views

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