Awesome q2a theme
Ask us anything
Toggle navigation
Email or Username
Password
Remember
Login
Register

I forgot my password
Activity
Q&A
Questions
Unanswered
Tags
Subjects
Users
Ask
Blogs
Previous Year
Exams
Recent questions and answers in Databases
0
votes
1
answer
Made Easy Test Series, DBMS, Functional Dependencies
answered
13 hours
ago
in
Databases
by
Abhisheksmile94
(
193
points)

23
views
databases
0
votes
0
answers
GATE 2001 DBMS
Suppose the adjacency relation of vertices in a graph is represented in a table Adj(X,Y). Which of the following queries cannot be expressed by a relational algebra expression of constant length? A List of all vertices adjacent to a given vertex B ... of less than three vertices D List all vertices reachable from a given vertex *Please elaborate all the solutions of this question.
asked
1 day
ago
in
Databases
by
donniedarko
(
21
points)

10
views
databases
0
votes
0
answers
Made Easy Test Series, DBMS, Normalization
Can anyone please explain how B) and D) are true? 2NF requires us to have no partial dependency on key for some nonkey attributes. 3NF requires us to have no transitive dependency OR X>Y non trivial dependencies where either X is SK or Y are all prime attributes. Can anyone please explain how this leads to options B and D being true? Thanks.
asked
1 day
ago
in
Databases
by
sankalpmittal
(
41
points)

8
views
databases
normalization
0
votes
0
answers
Made easy test series
how? can u plese draw them?
asked
3 days
ago
in
Databases
by
Salla shivateja
(
19
points)

19
views
testseries
0
votes
1
answer
ME Test Series
I have a doubt, How many rows will be returned when All values of R2.A will be Null….in this case number of rows Natural Join should give 0 rows ….what will be minimum number of rows???
answered
4 days
ago
in
Databases
by
ashutoshbsathe
(
5
points)

16
views
naturaljoin
0
votes
0
answers
Elmsari Fundamentals , Normalisation
Consider the universal relation A = {P,Q,R,S,T,U,V,W,X,Y,Z} and the set of functional dependencies FD's = { PQ > R, R > ST, Q > U, U > VW, S> XY }. What is the key for A. Decompose A into 2NF and 3 NF relations
asked
6 days
ago
in
Databases
by
Lucifer2440
(
5
points)

10
views
databases
normalization
0
votes
1
answer
TGA test series
Consider the following table P and Q .In table P, A is Primary key and B is foreign key referencing C in table Q with on delete Cascade.In table Q C is primary key and D is foreign key referencing A in table P with on delete Cascade.in order to delete record (2,6) from the table P.the ... 9 6 (Q C D 1 1 6 2 2 1 9 7 5 9 7 1 Last row of P is blanck by mistake it is added..ignore it)
answered
6 days
ago
in
Databases
by
Abhisheksmile94
(
193
points)

27
views
testseries
0
votes
0
answers
Joins in Relational Algebra (Self Doubt) while reading Elmasri Navathe
asked
6 days
ago
in
Databases
by
shubhojit1412
(
5
points)

15
views
joins
naturaljoin
0
votes
0
answers
Database management systems
If a schedule is given and it is asked whether the given schedule is serializable or not, is it asking about conflict serializability or view serializability? And when it is asked about the precedence graph, is it about the precedence graph that we draw to check conflict serializability or the one for view serializability?
asked
6 days
ago
in
Databases
by
Abhilash Behera
(
5
points)

10
views
selfdoubt
+1
vote
1
answer
GATEBOOK TS (DB)
$Given\ statement:$ Wound  wait and wait  die algorithms are pessimistic deadlock avoidance algorithms and can cause more transaction aborts than needed. My doubt: Yes I totally agree that they are pessimistic deadlock avoidance algorithms but how can they directly ... of transactions that will be aborted in the waitdie method. This should be the right statement. Is it not ?
answered
Jan 8
in
Databases
by
StoneHeart
(
735
points)

174
views
databases
transactions
deadlock
0
votes
1
answer
Ace test series
Ace say answer is C….but i find it incorrect...Please confirm if A is valid or C is valid answer
answered
Jan 8
in
Databases
by
Abhisheksmile94
(
193
points)

25
views
candidatekeys
0
votes
1
answer
FULL OUTER JOIN
Can anyone please explain how minimum number of tuples in case of Full Outer Join is max(m,n) using a proper example?
answered
Jan 8
in
Databases
by
Abhisheksmile94
(
193
points)

12
views
databases
0
votes
1
answer
Applied test Series DBMS
Consider the following relation R with attributes as A, B, C, D, and E with functional dependencies (FDs) as marked below: For example, the arrow coming from attribute B is towards the attribute C, therefore, the FD will be B > C. Which of the ... prime attributes. Therefore, the relation R is neither in 2NF nor in 3NF. Hence, the correct options are (iii), and (iv).
answered
Jan 7
in
Databases
by
Sgr007
(
21
points)

39
views
testseries
databases
0
votes
0
answers
The database system then writes out enough information to disk
asked
Jan 7
in
Databases
by
Tara22
(
13
points)

12
views
databases
0
votes
0
answers
Gate applied course
If an ER model says E having at least one multivalued attribute is converted into relational model say R then what will be the number of simple candidate key possible in R if E has only single attribute as candidate key? A) 0 B) exactly 1 c) more than 1 d) can’t say
asked
Jan 6
in
Databases
by
Gopichandankem
(
5
points)

21
views
databases
0
votes
0
answers
why we cannot undo a committed transaction
We have the log file that has all information to undo this committed transaction, so why it says we cannot? once a transaction has committed we cannot undo its effect by aborting it.
asked
Jan 6
in
Databases
by
Tara22
(
13
points)

17
views
databases
+1
vote
1
answer
NPTEL Assignment Question
S1 : r1(x),r2(x),w2(x),r3(x),w1(x), w2(y),r3(y),w3(x) S2 : r2(x),r1(x),w1(x),w2(x),w2(y),r3(x),w3(x),r3(y) The answer Says Both of them are view equivalent. My Doubt is that there Initial Read Don't ... first and In S2 T2 is reding it first. Same doubt as in this question https://csedoubts.gateoverflow.in/6351/nptelviewserialisability but it is unclear even in this.
answered
Jan 4
in
Databases
by
Abhisheksmile94
(
193
points)

23
views
databases
serializablity
0
votes
1
answer
THE GATE ACADEMY ts
Does B+ tree support random access?
answered
Jan 3
in
Databases
by
Abhisheksmile94
(
193
points)

32
views
databases
0
votes
0
answers
Allowed Functional Dependencies in DBMS
Why functional dependencies of the from NonPrime → Prime, are not allowed, I had encountered this logic in Made Easy Test Series and was unable to imagine a contradiction for this statement. Explanation with example would be appreciated.
asked
Jan 1
in
Databases
by
ronak.ladhar
(
5
points)

13
views
normalization
selfdoubt
0
votes
3
answers
ACE TEST SERIES: DBMS
The number of serial schedules which are view equal to schedule(s) but not conflict equal to schedule(s) are ________.
answered
Jan 1
in
Databases
by
Karan Negi
(
5
points)

95
views
databases
0
votes
1
answer
Made Easy Test series Database Q1
Assume S is a schedule that has both read and write operations with different transactions and different data variables. Also assume all the operations are atomic in nature. Which of the following are true? S with no dirty read then S is ... . S with no dirty read then S is conflict serializable schedule S with no dirty read then S is strict serializable.
answered
Dec 30, 2020
in
Databases
by
anurags228
(
23
points)

38
views
databases
0
votes
0
answers
Self doubt  2 Phase Locking
Does 2 Phase Locking Protocol ensures a Schedule as recoverable?
asked
Dec 30, 2020
in
Databases
by
mani312
(
5
points)

9
views
databases
2phaselocking
0
votes
0
answers
restore/recover
What's the difference between recover' and restore'? can we use recover' instead of restore' here? If the transaction does not complete its execution, the database system restores the old values from the log to make it appear as though the ... specifically, it is handled by a component of the database called the recovery system, which we describe in detail in Chapter 19.
asked
Dec 28, 2020
in
Databases
by
Tara22
(
13
points)

19
views
databases
0
votes
0
answers
GATE 2017 SET 1 Question 42
What is “Timestamp wrap around” in Timestamp Ordering Concurrency Control?
asked
Dec 28, 2020
in
Databases
by
Praddyumn
(
5
points)

12
views
databases
0
votes
1
answer
Self_doubts#
Lets consider a relation R(A,B,C,D) following are the functional dependencies on the relation R. AB > CD BC > AD AC > D My doubt is whether the functional dependency AC >D is in 2NF or not? Here {AB, BC} are Candidate Keys.
answered
Dec 27, 2020
in
Databases
by
Sahil91
(
645
points)

14
views
normalization
0
votes
0
answers
Gate Previous Year
R(A,B,C,D) is a relation. Which of the following does not have a lossless join, dependency preserving BCNF decomposition? (a) A→ B, B → CD (b) A → B, B→C, C→ D (c) AB→ C, C→ AD (d) A → BCD
asked
Dec 26, 2020
in
Databases
by
Rishav Chetan
(
9
points)

6
views
normalization
+1
vote
1
answer
GATE200882 Video Solution
Consider the following $ER$ diagram The minimum number of tables needed to represent $M$, $N$, $P$, $R1$, $R2$ is $2$ $3$ $4$ $5$
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

7
views
gate2008
databases
erdiagram
normal
videosolution
+1
vote
1
answer
GATE200575 Video Solution
Let $E_1$ and $E_2$ be two entities in an $E/R$ diagram with simplevalued attributes. $R_1$ and $R_2$ are two relationships between $E_1$ and $E_2$, where $R_1$ is onetomany and $R_2$ is manytomany. $R_1$ and $R_2$ do not have ... of their own. What is the minimum number of tables required to represent this situation in the relational model? $2$ $3$ $4$ $5$
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

5
views
gate2005
databases
erdiagram
normal
videosolution
+1
vote
1
answer
GATE2004IT73 Video Solution
Consider the following entity relationship diagram $(ERD)$, where two entities $E1$ and $E2$ have a relation $R$ of cardinality 1:m. The attributes of $E1$ are $A11$, $A12$ and $A13$ where $A11$ is the key attribute. The attributes of $E2$ are $A21$ ... normal form ($3NF$) is designed from the above $ERD$. The number of tables in the database is $2$ $3$ $5$ $4$
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

9
views
gate2004it
databases
erdiagram
normal
videosolution
+1
vote
1
answer
GATE2015141 Video Solution
Consider an EntityRelationship $(ER)$ model in which entity sets E$_{1}$ and E$_{2}$ are connected by an m:n relationship R$_{12}$. E$_{1}$ and E$_{3}$ are connected by a 1 : n (1 on the side of E$_{1}$ ... relational model is derived from the above $ER$ model, then the minimum number of relations that would be generated if all relation are in $3NF$ is________________.
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

9
views
gate20151
databases
erdiagram
normal
numericalanswers
videosolution
+1
vote
1
answer
GATE19982.19 Video Solution
Which of the following query transformations (i.e., replacing the l.h.s. expression by the r.h.s expression) is incorrect? R1 and R2 are relations, C1 and C2 are selection conditions and A1 and A2 are attributes of R1. A. ... $\pi_{A_1} \left(\sigma_{C_1}\left(R_1\right)\right) \to \sigma_{C_1} \left(\pi_{A_1}\left(R_1\right)\right)$
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

13
views
gate1998
databases
relationalcalculus
normal
videosolution
+1
vote
1
answer
GATE19991.18, ISRO201653 Video Solution
Consider the join of a relation $R$ with a relation $S$. If $R$ has $m$ tuples and $S$ has $n$ tuples then the maximum and minimum sizes of the join respectively are $m+n$ and $0$ $mn$ and $0$ $m+n$ and $mn$ $mn$ and $m+n$
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

10
views
gate1999
databases
relationalalgebra
easy
isro2016
videosolution
+1
vote
1
answer
GATE2007IT65 Video Solution
Consider a selection of the form $\sigma_{A\leq 100} (r)$, where $r$ is a relation with $1000$ tuples. Assume that the attribute values for $A$ among the tuples are uniformly distributed in the interval $[0, 500].$ Which one of the following options is the best estimate of the number of tuples returned by the given selection query ? $50$ $100$ $150$ $200$
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

8
views
gate2007it
databases
relationalcalculus
probability
normal
videosolution
+1
vote
1
answer
GATE200413 Video Solution
Let $R_1 \left(\underline{A}, B, C\right)$ and $R_2\left(\underline{D}, E \right) $ be two relation schema, where the primary keys are shown underlined, and let C be a foreign key in $R_1$ referring to $R_2$. Suppose there is no violation of the above referential ... $\Pi_D \left(r_1 \bowtie_{C \neq D}r_2\right)$ $\Pi_C \left(r_1 \bowtie_{C = D}r_2\right)$
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

8
views
gate2004
databases
relationalcalculus
easy
videosolution
+1
vote
1
answer
GATE200451 Video Solution
Consider the relation Student (name, sex, marks), where the primary key is shown underlined, pertaining to students in a class that has at least one boy and one girl. What does the following relational algebra expression produce? (Note: $\rho$ ... of girl students with marks not less than some boy student names of girl students with more marks than all the boy students
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

13
views
gate2004
databases
relationalalgebra
normal
videosolution
+1
vote
1
answer
GATE200759 Video Solution
Information about a collection of students is given by the relation $\text{studInfo(}\underline{\text{studId}},\text{ name, sex)}$. The relation $\text{enroll(}{\text{studId}},{\text{ courseId}})$ gives which student has enrolled for ( ... Courses in which a proper subset of female students are enrolled. Courses in which only male students are enrolled. None of the above
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

9
views
gate2007
databases
relationalalgebra
normal
videosolution
0
votes
0
answers
consistence constraints
The text below is from Silberschatz book. Can you please explain how consistence constraints can be verified by integrity constraints? Ensuring consistency for an individual transaction is the responsibility of the application programmer who codes the transaction. This task may be facilitated by automatic testing of integrity constraints, as we discussed in Section 4.4.
asked
Dec 26, 2020
in
Databases
by
Tara22
(
13
points)

6
views
databases
+1
vote
1
answer
GATE2014330 Video Solution
Consider the relational schema given below, where eId of the relation dependent is a foreign key referring to empId of the relation employee. Assume that every employee has at least one associated dependent in the dependent relation. employee (empId, ... is greater than that of some dependent. all dependents. some of his/her dependents. all of his/her dependents.
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

8
views
gate20143
databases
relationalalgebra
normal
videosolution
+1
vote
1
answer
GATE200868 Video Solution
Let R and S be two relations with the following schema $R(\underline{P,Q}, R1, R2, R3)$ $S(\underline{P,Q}, S1, S2)$ where $\left\{P, Q\right\}$ is the key for both schemas. Which of the following queries are equivalent? $\Pi_P \left(R \bowtie S\right)$ ... Only I and II Only I and III Only I, II and III Only I, III and IV
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

9
views
gate2008
databases
relationalalgebra
normal
videosolution
+1
vote
1
answer
GATE201243 Video Solution
Suppose $R_{1} (\underline{A}, B)$ and $R_{2} (\underline{C}, D) $ are two relation schemas. Let $r_{1}$ and $r_{2}$ be the corresponding relation instances. $B$ is a foreign key that refers to $C$ in $R_{2}$. If data in $r_{1}$ and $r_{2}$ satisfy referential ... $\prod_{B}(r_{1}) = \prod _{C}(r_{2})$ $\prod_{B}(r_{1})  \prod _{C}(r_{2}) \neq \varnothing$
answered
Dec 26, 2020
in
Databases
by
amitkhurana512
(
35
points)

9
views
gate2012
databases
relationalalgebra
normal
videosolution
To see more, click for all the
questions in this category
.
Quick search syntax
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
Welcome to GATE CSE Doubts, where you can ask questions and receive answers from other members of the community.
Top Users
2021 Jan 11  17
zxy123
450 Points
Abhisheksmile94
78 Points
kalin
60 Points
donniedarko
16 Points
Abhineet Singh
8 Points
Allica
8 Points
Shaik Masthan
8 Points
Enolx.21
6 Points
Sahil91
6 Points
aditi19
6 Points
Weekly Top User (excluding moderators) will get free access to
GATE Overflow Test Series for GATE 2021
Recent Posts
New GATEOverflow PDFs
Guidelines to users
No Recent Blog Comments
Recent questions and answers in Databases
8,957
questions
3,118
answers
14,337
comments
95,787
users