Recent questions and answers in Databases / GATE Overflow for GATE CSE

0 votes

1 answer

1

Minimal Cover
Consider R(A,B,C,D,E,H) be a relational schema with the following functional dependencies: A->BC, CD->E, E->C, D->AEH, ABH->BD, DH->BC Find minimal cover ?

Consider R(A,B,C,D,E,H) be a relational schema with the following functional dependencies:A->BC, CD->E, E->C, D->AEH, ABH->BD, DH->BCFind minimal cover ?

manishankarkanrar

115 views

manishankarkanrar answered 6 days ago

0 votes

1 answer

2

Number of Super Keys
R(A1, A2,A3,A4....AN). How many super keys possible in relation? If (A1 is candidate key, A2 is candidate key, A3 is candidate key)

R(A1, A2,A3,A4....AN). How many super keys possible in relation? If (A1 is candidate key, A2 is candidate key, A3 is candidate key)

manishankarkanrar

65 views

manishankarkanrar answered 6 days ago

0 votes

0 answers

3

Relational Database
Give an appropriate tree-structure diagram for the following relational database: Employee (person_name, street, city) Works (person_name, company_name, salary) Company (company_name, city) Manages (person_name, manager_name)

Give an appropriate tree-structure diagram for the following relational database:Employee (person_name, street, city)Works (person_name, company_name, salary)Company (com...

peter09

46 views

peter09 asked Apr 16

0 votes

0 answers

4

RBR Normalisation example problem
In on of the examples shown by RBR sir, under Normalization I think he did this problem incorrectly, Given relation R(ABC) and fd: AB->C and C->A, convert it into 2NF For this question, the answer according to RBR sir was that the ... "BC", therefore we need to split the tables into AC and ABC is what my solution. Kindly correct me if I am wrong

In on of the examples shown by RBR sir, under Normalization I think he did this problem incorrectly, Given relation R(ABC) and fd: AB->C and C->A, convert it into 2NFFor ...

nareshit

43 views

nareshit asked Apr 15

0 votes

0 answers

5

If P and Q are predicates and P is the relational algebra expression, then which of the following equivalence are valid ? (1) σP(σQ(e)) = σQ(σP(e)). (2) σP(σQ(e)) = σP ∪ Q(e) (3) σP(σP(e)) = σP V Q (4) All of these

SandeepKumar147

57 views

SandeepKumar147 asked Apr 8

0 votes

1 answer

6

Relation R(A1, A2, A3 ..... An) n attributes. On this relation m simple candidate key (m ≤ n). How many super keys possible in this relation? A. 2m – 1 B. (2n – 1) ⋅ 2n-m C. 2n – 1 D. (2m – 1) 2n-m

꧁༒☬ĿọŗԀ 🆂🅷🅸🆅🅰☬༒꧂

90 views

꧁༒☬ĿọŗԀ 🆂🅷🅸🆅🅰☬༒꧂ answered Apr 6

0 votes

0 answers

7

Can a candidate key for a composite attribute be called a composite key?
Let's take an example of student entity type Name Class Section Address (Line1, Line2, City, State, Country, PinCode) Since composite attribute holds multiple atomic attributes, such that the group is treated as ... (ignoring the semantics) the combinations like {Class, Section} {Class, Address} {Name, Class, Section}

Let's take an example of student entity typeNameClassSectionAddress (Line1, Line2, City, State, Country, PinCode)Since composite attribute holds multiple atomic attribute...

tbhaxor

59 views

tbhaxor asked Apr 4

37 votes

5 answers

8

GATE CSE 2018 | Question: 42
Consider the following four relational schemas. For each schema , all non-trivial functional dependencies are listed, The bolded attributes are the respective primary keys. $\text{Schema I:}$ Registration(rollno, courses) Field courses' is a set-valued attribute containing the ... $\text{Schema I}$ $\text{Schema II}$ $\text{Schema III}$ $\text{Schema IV}$

Consider the following four relational schemas. For each schema , all non-trivial functional dependencies are listed, The bolded attributes are the respective primary key...

SarthakShastri

12.0k views

SarthakShastri answered Apr 4

1 votes

2 answers

9

ISI2017-PCB-CS-3-a
Let $R(A,B,C)$ be a relation with primary key $(A)$ and $S(A, D, E)$ a relation with primary key $(A, D)$. Each of the relations has $n$ tuples. If the number of tuples in $R \: \text{ natural join } S$ is $m$, then determine the number of tuples in $R$ $\text{ natural left outer join } S$.

Let $R(A,B,C)$ be a relation with primary key $(A)$ and $S(A, D, E)$ a relation with primary key $(A, D)$. Each of the relations has $n$ tuples. If the number of tuples i...

Abhay123

501 views

Abhay123 answered Mar 31

0 votes

1 answer

10

ISI2020-PCB-CS: 5
In a conference, the relation, $\textsf{registered (participant, topic)}$ stores the names of participants and the topics registered by them. The primary key for this relation is $\textsf{(participant, topic)}.$ ... . Which strategy is faster for $x=3000?$ Justify your answer. Which strategy has less disk access time? Justify your answer.

In a conference, the relation, $\textsf{registered (participant, topic)}$ stores the names of participants and the topics registered by them. The primary key for this rel...

Abhay123

150 views

Abhay123 answered Mar 31

1 votes

1 answer

11

ISI 2021 | PCB CS | Question: 9
In relational algebra, for any pair of relations $R_{1}$ and $R_{2}$, the standard division operation is denoted by $\div$ ...

In relational algebra, for any pair of relations $R_{1}$ and $R_{2}$, the standard division operation is denoted by $\div$ and defined as follows: $$ R_{1} \div R_{2}=\pi...

Abhay123

269 views

Abhay123 answered Mar 31

0 votes

1 answer

12

S: r3(x) r3(y) w3(x) W2(x) r1(x) w2(y) w3(y) w1(y) How many serial schedules are not view equal to schedule S?

L.E.O

147 views

L.E.O answered Mar 29

0 votes

1 answer

13

Explain why BCNF is said to be improved 3NF.

prasantkr.singh

116 views

prasantkr.singh answered Mar 17

0 votes

0 answers

14

File organisation and indexing (DBMS)

Suryadip

106 views

Suryadip asked Mar 9

3 votes

2 answers

15

GATE CSE 2024 | Set 2 | Question: 16
Which of the following file organizations is/are $\text{I/O}$ efficient for the scan operation in $\text{DBMS}$? Sorted Heap Unclustered tree index Unclustered hash index

Which of the following file organizations is/are $\text{I/O}$ efficient for the scan operation in $\text{DBMS}$?SortedHeapUnclustered tree indexUnclustered...

sanjeet24

2.4k views

sanjeet24 answered Mar 5

0 votes

0 answers

16

#TOC

Çșȇ ʛấẗẻ

57 views

Çșȇ ʛấẗẻ asked Feb 24

0 votes

0 answers

17

#dbms

Çșȇ ʛấẗẻ

91 views

Çșȇ ʛấẗẻ asked Feb 24

0 votes

0 answers

18

NPTEL DBMS (Introduction to Database systems)course Assignment 10: Topic Database Indexing
Use the following information to answer Questions 7 and 8. A sorted file has the following details: Number of records = 13,10,720; record length = 200 bytes; size of the primary key field = 13 bytes; size of ... of blocks in the first level index file is: a)131072 b)1311 c)1310 d)1286 Accepted Answers: 1286

Use the following information to answer Questions 7 and 8.A sorted file has the following details: Number of records = 13,10,720; record length = 200 bytes;size of the pr...

RishabhSahu325

147 views

RishabhSahu325 asked Feb 22

1 votes

3 answers

19

GATE CSE 2024 | Set 1 | Question: 34
The symbol $\rightarrow$ indicates functional dependency in the context of a relational database. Which of the following options is/are TRUE? $(X, Y) \rightarrow(Z, W)$ implies $X \rightarrow(Z, W)$ $(X, Y) \rightarrow(Z, W)$ ... $(X, W) \rightarrow Z$ $(X \rightarrow Y$ and $Y \rightarrow Z)$ implies $X \rightarrow Z$

The symbol $\rightarrow$ indicates functional dependency in the context of a relational database. Which of the following options is/are TRUE?$(X, Y) \rightarrow(Z, W)$...

GauravRajpurohit

2.2k views

GauravRajpurohit answered Feb 18

0 votes

2 answers

20

GATE DS&AI 2024 | Question: 21
Consider the following two tables named Raider and Team in a relational database maintained by a Kabaddi league. The attribute ID in table Team references the primary key of the Raider table, ID. Raider ID Name Raids RaidPoints $1$ Arjun $200$ $250$ $2$ ... Jaipur" AND RaidPoints > 200; The number of rows returned by this query is $\_\_\_\_\_\_\_\_$.

Consider the following two tables named Raider and Team in a relational database maintained by a Kabaddi league. The attribute ID in table Team references the primary key...

Hira Thakur

892 views

Hira Thakur answered Feb 17

0 votes

1 answer

21

GATE DS&AI 2024 | Question: 36
Given the relational schema $R=(U, V, W, X, Y, Z)$ and the set of functional dependencies: \[ \{U \rightarrow V, U \rightarrow W, W X \rightarrow Y, W X \rightarrow Z, V \rightarrow X\} \] Which of the following functional dependencies can be derived from the above set? $V W \rightarrow Y Z$ $W X \rightarrow Y Z$ $V W \rightarrow U$ $V W \rightarrow Y$

Given the relational schema $R=(U, V, W, X, Y, Z)$ and the set of functional dependencies:\[\{U \rightarrow V, U \rightarrow W, W X \rightarrow Y, W X \...

Hira Thakur

882 views

Hira Thakur answered Feb 17

2 votes

3 answers

22

GATE CSE 2024 | Set 1 | Question: 11
In a $\mathrm{B}+$ tree, the requirement of at least half-full $(50 \%)$ node occupancy is relaxed for which one of the following cases? Only the root node All leaf nodes All internal nodes Only the leftmost leaf node

In a $\mathrm{B}+$ tree, the requirement of at least half-full $(50 \%)$ node occupancy is relaxed for which one of the following cases?Only the root nodeAll leaf nodesAl...

KASHIF_RAHMAN

2.3k views

KASHIF_RAHMAN answered Feb 17

1 votes

2 answers

23

GATE CSE 2024 | Set 1 | Question: 10
Let $\mathrm{S}$ be the specification: "Instructors teach courses. Students register for courses. Courses are allocated classrooms. Instructors guide students." Which one of the following $\mathrm{ER}$ diagrams CORRECTLY represents $\mathrm{S}$? $\text{(i)}$ $\text{(ii)}$ $\text{(iii)}$ $\text{(iv)}$

Let $\mathrm{S}$ be the specification: "Instructors teach courses. Students register for courses. Courses are allocated classrooms. Instructors guide students." Which one...

KASHIF_RAHMAN

2.1k views

KASHIF_RAHMAN answered Feb 17

3 votes

2 answers

24

GATE CSE 2024 | Set 1 | Question: 12
Which of the following statements about a relation $\mathbf{R}$ in first normal form $\text{(1NF)}$ is/are TRUE? $\mathbf{R}$ can have a multi-attribute key $\mathbf{R}$ cannot have a foreign key $\mathbf{R}$ cannot have a composite attribute $\mathbf{R}$ cannot have more than one candidate key

Which of the following statements about a relation $\mathbf{R}$ in first normal form $\text{(1NF)}$ is/are TRUE?$\mathbf{R}$ can have a multi-attribute key$\mathbf{R}$ ca...

iarpitmishra

3.6k views

iarpitmishra answered Feb 17

1 votes

1 answer

25

GATE CSE 2024 | Set 1 | Question: 36
Consider the following read-write schedule $\text{S}$ over three transactions $T_{1}, T_{2}$, and $T_{3}$ ... to $\text{S}$? $T_{1} T_{2} T_{3}$ $T_{1} T_{3} T_{2}$ $T_{3} T_{2} T_{1}$ $T_{3} T_{1} T_{2}$

Consider the following read-write schedule $\text{S}$ over three transactions $T_{1}, T_{2}$, and $T_{3}$, where the subscripts in the schedule indicate trans...

Hira Thakur

2.3k views

Hira Thakur answered Feb 16

2 votes

1 answer

26

GATE CSE 2024 | Set 2 | Question: 35
The relation schema, Person (pid, city), describes the city of residence for every person uniquely identified by pid. The following relational algebra operators are available: selection, projection, cross product, and rename. To find the list of cities ... above operators, the minimum number of cross product operations that must be used is $1$ $2$ $3$ $4$

The relation schema, Person (pid, city), describes the city of residence for every person uniquely identified by pid. The following relational algebra oper...

Deepak Poonia

2.3k views

Deepak Poonia answered Feb 16

1 votes

1 answer

27

GATE CSE 2024 | Set 2 | Question: 17
Which of the following statements about the Two Phase Locking ($2 \mathrm{PL}$) protocol is/are TRUE? $2 \mathrm{PL}$ permits only serializable schedules With $2 \mathrm{PL}$, a transaction always locks the data item being read or ... , no more locks on any data item can be obtained inside that transaction A deadlock is possible with $2 \mathrm{PL}$

Which of the following statements about the Two Phase Locking ($2 \mathrm{PL}$) protocol is/are TRUE?$2 \mathrm{PL}$ permits only serializable schedulesWith $...

supreetshukla

2.0k views

supreetshukla answered Feb 16

1 votes

1 answer

28

GATE CSE 2024 | Set 2 | Question: 46
A functional dependency $F: X \rightarrow Y$ is termed as a useful functional dependency if and only if it satisfies all the following three conditions: $\text{X}$ is not the empty set. $\text{Y}$ is not the empty set. Intersection ... set. For a relation $\text{R}$ with $4$ attributes, the total number of possible useful functional dependencies is __________.

A functional dependency $F: X \rightarrow Y$ is termed as a useful functional dependency if and only if it satisfies all the following three conditions:$\text{X}$ is not ...

supreetshukla

1.8k views

supreetshukla answered Feb 16

1 votes

2 answers

29

GATE CSE 2024 | Set 2 | Question: 9
Once the $\text{DBMS}$ informs the user that a transaction has been successfully completed, its effect should persist even if the system crashes before all its changes are reflected on disk. This property is called durability atomicity consistency isolation

Once the $\text{DBMS}$ informs the user that a transaction has been successfully completed, its effect should persist even if the system crashes before all...

Deepak Poonia

2.2k views

Deepak Poonia answered Feb 16

1 votes

1 answer

30

GATE CSE 2024 | Set 1 | Question: 25
Consider the following two relations, $R(A, B)$ and $S(A, C)$: $R$ $A$ $B$ $10$ $20$ $20$ $30$ $30$ $40$ $30$ $50$ $50$ $95$ $S$ $A$ $C$ $10$ $90$ $30$ $45$ $40$ $80$ The total number of tuples obtained by evaluating the following expression $\sigma_{B<C}\left(R \bowtie_{R . A=S . A} S\right)$ is ___________.

Consider the following two relations, $R(A, B)$ and $S(A, C)$:$R$$A$$B$$10$$20$$20$$30$$30$$40$$30$$50$$50$$95$$S$$A$$C$$10$$90$$30$$45$$40$$80$The total number of tuples...

Hira Thakur

1.8k views

Hira Thakur answered Feb 16

1 votes

1 answer

31

GATE CSE 2024 | Set 2 | Question: 10
In the context of owner and weak entity sets in the $\text{ER}$ (Entity-Relationship) data model, which one of the following statements is TRUE? The weak entity set MUST have total participation in the identifying ... in the identifying relationship Neither weak entity set nor owner entity set MUST have total participation in the identifying relationship

In the context of owner and weak entity sets in the $\text{ER}$ (Entity-Relationship) data model, which one of the following statements is TRUE?The weak entity set MUST h...

supreetshukla

1.9k views

supreetshukla answered Feb 16

6 votes

3 answers

32

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 14
A B-Tree of order $m$ is an $m$-way search tree. What is the minimum number of keys that can be stored on the leaf level of a B-Tree of order 20 with 3 levels? (Note: the root of a tree counts as its first level)

A B-Tree of order $m$ is an $m$-way search tree. What is the minimum number of keys that can be stored on the leaf level of a B-Tree of order 20 with 3 levels? (Note: th...

Praveenjha802

681 views

Praveenjha802 answered Feb 7

0 votes

1 answer

33

Memory Based GATE DA 2024 | Question: 16
Consider a relation R: \[ \begin{aligned} & R(U, V, W, X, Y, Z) \\ & F=\left\{ \begin{array}{l} U \rightarrow V \\ U \rightarrow W \\ WX \rightarrow Y \\ WX \rightarrow Z \\ V \rightarrow X \end ... be deduced. Which of the following options is correct? $VW \rightarrow U$ $VW \rightarrow Y$ $VW \rightarrow YZ$ $WX \rightarrow YZ$

Consider a relation R:\[\begin{aligned}& R(U, V, W, X, Y, Z) \\& F=\left\{\begin{array}{l} U \rightarrow V \\ U \rightarrow W \\ WX \rightarrow Y \\�...

Lakshmi Narayana404

222 views

Lakshmi Narayana404 answered Feb 6

4 votes

1 answer

34

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 13
Division operator in relational algebra is appropriate to handle which of the following query types? employees work on at most one of the critical projects employees work on any one of the critical projects employees work on at least one of the critical projects employees work on all the critical projects

Division operator in relational algebra is appropriate to handle which of the following query types?employees work on at most one of the critical projectsemployees work o...

GO Classes

386 views

GO Classes answered Feb 5

4 votes

0 answers

35

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 40
Consider the following schema (primary keys are underlined): Which of the following queries returns the department numbers of those departments for which there are no courses being offered?

Consider the following schema (primary keys are underlined):Which of the following queries returns the department numbers of those departments for which there are no cour...

GO Classes

328 views

GO Classes asked Feb 5

9 votes

1 answer

36

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 41
Consider the following lock requests in the Table below. And note that: $\mathrm{S}(\cdot)$ and $\mathrm{X}(\cdot)$ stand for 'shared lock' and 'exclusive lock', respectively. $T_1, T_2, T_3, T_4$, and $T_5$ represent five ... dead('-'). Select all that are correct. At t3: a At t6: b At t7: a At t8: -

Consider the following lock requests in the Table below. And note that:$\mathrm{S}(\cdot)$ and $\mathrm{X}(\cdot)$ stand for 'shared lock' and 'exclusive lock', respectiv...

GO Classes

743 views

GO Classes answered Feb 5

6 votes

1 answer

37

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 50
Consider the following database relation: $\mathrm{R}=(\mathrm{SFLNGCRW} \mathrm{H})=(\mathrm{S}$ : SID, F: First Name, L: Last Name, N: Number of Units, G: GPA, C: Course (of teaching), R ... only one applied? SID determines Rating Rating determines Wage Rating determines Course Rating and First Name determine Wage and Hours of Work

Consider the following database relation: $\mathrm{R}=(\mathrm{SFLNGCRW} \mathrm{H})=(\mathrm{S}$ : SID, F: First Name, L: Last Name, N: Number of Units, G: GPA, C: Cours...

GO Classes

362 views

GO Classes answered Feb 5

1 votes

2 answers

38

Consider a schema R(A, B, C, D, E, F) and functional dependencies A → B, C → D, and E → F. The number of superkeys of this schema is ____

amityadav

271 views

amityadav answered Feb 3

5 votes

5 answers

39

ISRO2020-51
The SQL query SELECT columns FROM TableA RIGHT OUTER JOIN TableB ON A.columnName = B.columnName WHERE A.columnName IS NULL returns the following: All rows in Table $\text{B}$, which meets equality condition above and, none from Table $\text{A}$ which meets the ... in Table $\text{B}$, which meets the equality condition All rows in Table $\text{A}$, which meets the equality condition

The SQL querySELECT columns FROM TableA RIGHT OUTER JOIN TableB ON A.columnName = B.columnName WHERE A.columnName IS NULLreturns the following:All rows in Table $\text{B}...

satyaAchar

3.6k views

satyaAchar answered Feb 1

tags	tag:apple
author	user:martin
title	title:apple
content	content:apple
exclude	-tag:apple
force match	+apple
views	views:100
score	score:10
answers	answers:2
is accepted	isaccepted:true
is closed	isclosed:true