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Recent questions and answers in Databases

Recent questions and answers in Databases

0 votes
0 answers 7 views
Made Easy DBMS Practice Set - Normalisation - Question 53
Let R be a relation. Which of the following comments about the relation R are correct ? R will necessarily have a composite key if R is in BCNF but not in 4NF If R is in 3NF and if every key of R is simple, then R is in BCNF If R is in BCNF and if R has at least one simple key , then R is in ... and if its every key is simple, then R is in 5NF a) 1 and 4 b) 2 and 3 c) 1, 2 and 3 d) 1, 2, 3 and 4
asked 5 days ago in Databases 10nikhilsharma01 5 points 7 views
0 votes
0 answers 5 views
Made Easy DBMS practice set - Normalization - Question 45
Redundancy is dangerous as it is a potentiad threat to data integrity consistency sufficiency both 1 and 2 Answer is 4 but why ?
asked 5 days ago in Databases 10nikhilsharma01 5 points 5 views
0 votes
0 answers 7 views
MADE EASY TEST SERIES DBMS 2022
I cannot understand why is option D) incorrect? Can anyone give an example of how in option D) first one can contain duplicate values and second one cannot ? Kindly help me. Thanks in advance
I cannot understand why is option D) incorrect? Can anyone give an example of how in option D) first one can contain duplicate values and second one cannot ? Kindly help me. Thanks in advance
asked Jun 12 in Databases KUSHAL CHAKRABORTY 5 points 7 views
0 votes
1 answer 16 views
ACE Academy Test series gate 2021
Consider the following relation R(XYZ) with X as the primary key and Z as the foreign key referencing X with a delete cascade. X Y Z X1 Y1 X7 X3 Y1 X2 X5 Y4 X3 X2 Y2 X1 X9 Y5 X3 X7 Y3 X8 X4 Y2 X2 Suppose tuple (X2, Y2, X1) is deleted, as a result what will be the number of tuples in R after deletion?
Consider the following relation R(XYZ) with X as the primary key and Z as the foreign key referencing X with a delete cascade. X Y Z X1 Y1 X7 X3 Y1 X2 X5 Y4 X3 X2 Y2 X1 X9 Y5 X3 X7 Y3 X8 X4 Y2 X2 Suppose tuple (X2, Y2, X1) is deleted, as a result what will be the number of tuples in R after deletion?
answered Jun 9 in Databases Subhajit Panday 11 points 16 views
0 votes
1 answer 10 views
Ace Academy test series gate 2021
A relation R (ABCDE) with functional dependency F= {AB ->CD, A->E, C->D} The decomposition of R into R1(ABC), R2(BCD) and R3(CDE) (i) lossless join (ii) lossy decomposition (iii) dependency preserving (iv) not dependency preserving (A) i & ii (B) i & iv (C) ii & iii (D) ii & iv
A relation R (ABCDE) with functional dependency F= {AB ->CD, A->E, C->D} The decomposition of R into R1(ABC), R2(BCD) and R3(CDE) (i) lossless join (ii) lossy decomposition (iii) dependency preserving (iv) not dependency preserving (A) i & ii (B) i & iv (C) ii & iii (D) ii & iv
answered Jun 9 in Databases Subhajit Panday 11 points 10 views
0 votes
1 answer 15 views
How to draw the serializability graph if transactions are getting commited
Consider the following (incomplete) schedule S: T1:R(X), T1:R(Y), T1:W(X), T2:R(Y), T3:W(Y), T1:W(X), T2:R(Y) If all three transactions eventually commit, show the serializability graph.
answered Jun 7 in Databases Subhajit Panday 11 points 15 views
0 votes
0 answers 5 views
this is my assignment
For the following information systems determine the entities of interest, their attributes and the relationships that exist between the entities. Draw the E-R diagram for the system. Peoples Information Systems for a village/ward(that stores information about peoples)
For the following information systems determine the entities of interest, their attributes and the relationships that exist between the entities. Draw the E-R diagram for the system. Peoples Information Systems for a village/ward(that stores information about peoples)
asked Jun 5 in Databases nasima0058 5 points 5 views
0 votes
0 answers 8 views
DBMS Serializability
Consider the following (incomplete) schedule S: T1:R(X), T1:R(Y), T1:W(X), T2:R(Y), T3:W(Y), T1:W(X), T2:R(Y) If all three transactions eventually commit, show the serializability graph.
Consider the following (incomplete) schedule S: T1:R(X), T1:R(Y), T1:W(X), T2:R(Y), T3:W(Y), T1:W(X), T2:R(Y) If all three transactions eventually commit, show the serializability graph.
asked Jun 3 in Databases Lekhraj 9 points 8 views
0 votes
0 answers 7 views
made easy online test series
here is the question. I think the minimum number of the table needed is 4 whereas 5 is given as the answer. please clear my doubt.
here is the question. I think the minimum number of the table needed is 4 whereas 5 is given as the answer. please clear my doubt.
asked Jun 2 in Databases Ulta_sidha 5 points 7 views
1 vote
1 answer 16 views
Tga test series
It is 2NF or not ? Just explain this portion.
It is 2NF or not ? Just explain this portion.
answered Jun 2 in Databases Deepakk Poonia (Dee) 1.7k points 16 views
0 votes
0 answers 8 views
Indexing (DBMS)
Lets suppose, we define a schema with no primary key but there is an attribute(s) with unique and not null constraints. Now default indexing i.e primary indexing is not possible here because of no primary key. Now, at the time of Database design, ... necessary to input records in sorted order? or is there any other way possible to apply clustering index over a given database file?
Lets suppose, we define a schema with no primary key but there is an attribute(s) with unique and not null constraints. Now default indexing i.e primary indexing is not possible here because of no primary key. Now, at the time of Database design, If i write ... is it necessary to input records in sorted order? or is there any other way possible to apply clustering index over a given database file?
asked May 30 in Databases bhardwaj.aakash_420 5 points 8 views
0 votes
0 answers 8 views
b)List all students taking at least one course that their mentor teaches.
Given the relational schemas: ENROLL(SID,C_No,Section) - SID and C_No represent student id number, course number respectively TEACH(TID,C_No,Section) - TID represents teacher id number ADVISE(TID,SID) TID is the mentor of SID PRE_REQ(C_No,PRE_C_No) - PRE_C_No is ... List the courses that student Anindya can enroll in, i.e., has passed the necessary prerequisite courses but not the course itself.
asked May 29 in Databases nasima0058 5 points 8 views
0 votes
0 answers 6 views
my sir give this assignment
Consider the following relations concerning a driving school. The primary key of each relation is in boldface. STUDENT(S_Name,Class_No,Th_Mark,Dr_Mark) S_Name - student name, Th-Mark - Theory mark, Dr_Mark - driving mark STUDENT_DRIVING_TEACHER(S_Name,Dr_T_Name) ... marks than average theory mark of class 8. f)Find the list of teachers who can drive all the vehicles.
Consider the following relations concerning a driving school. The primary key of each relation is in boldface. STUDENT(S_Name,Class_No,Th_Mark,Dr_Mark) S_Name - student name, Th-Mark - Theory mark, Dr_Mark - driving mark STUDENT_DRIVING_TEACHER(S_Name,Dr_T_Name) Dr_T_Name - driving ... more marks than average theory mark of class 8. f)Find the list of teachers who can drive all the vehicles.
asked May 29 in Databases nasima0058 5 points 6 views
0 votes
0 answers 5 views
Selfdoubt(Relational Algebra and SQL)
Is the JOIN operations(natural , left , right) in relational algebra and SQL same or is there any difference based on the condition? Please provide reference.
Is the JOIN operations(natural , left , right) in relational algebra and SQL same or is there any difference based on the condition? Please provide reference.
asked May 27 in Databases samir757 29 points 5 views
0 votes
0 answers 6 views
Self-doubt(DBMS)
How to find the number of relations required for a self-referential relationship with all the cardinalities mapped with total and partial participation? Please provide links to the same.
How to find the number of relations required for a self-referential relationship with all the cardinalities mapped with total and partial participation? Please provide links to the same.
asked May 27 in Databases samir757 29 points 6 views
1 vote
1 answer 49 views
Normalization,2NF
Suppose, R(ABCDE) is a relation, and {AB,CD} are the candidate keys, then: the functional dependency, AC->E a partial dependency? Edit: Actually i wanted to ask if AC->E is in 2NF?
Suppose, R(ABCDE) is a relation, and {AB,CD} are the candidate keys, then: the functional dependency, AC->E a partial dependency? Edit: Actually i wanted to ask if AC->E is in 2NF?
answered May 24 in Databases Deepakk Poonia (Dee) 1.7k points 49 views
0 votes
0 answers 7 views
what is the degree when is uses the same entity more then once. same entity two time or three time or more .
what is the degree of recursive relationship in ER diagram.
asked May 22 in Databases its_vv 5 points 7 views
1 vote
2 answers 58 views
Made easy workbook
Suppose we have two entity sets person, Email and use a relationship Owns. A person own atmost one email account but an email account can be owned by multiple persons. Which of the following is an ER diagram based on above description.
Suppose we have two entity sets person, Email and use a relationship Owns. A person own atmost one email account but an email account can be owned by multiple persons. Which of the following is an ER diagram based on above description.
answered May 12 in Databases immanujs 5 points 58 views
0 votes
0 answers 10 views
Made Easy chapter 1 question 12
Find the minimum number of tables in the above ER diagram.
Find the minimum number of tables in the above ER diagram.
asked May 6 in Databases Amaterasu07 5 points 10 views
0 votes
0 answers 11 views
gate 2001 DBMS(normalization)
R(A,B,C,D) is a relation. FD given is:{ AB->C , C->AD } is it in 2NF? is it in 3NF?
R(A,B,C,D) is a relation. FD given is:{ AB->C , C->AD } is it in 2NF? is it in 3NF?
asked May 2 in Databases rishabh8797 5 points 11 views
0 votes
0 answers 7 views
Functional Dependency
A relation R(A,B,C) has FD A $\rightarrow$ B and other relation M(A, B) has FD A $\rightarrow$ B. Does relation R and M have equivalent FD ?
A relation R(A,B,C) has FD A $\rightarrow$ B and other relation M(A, B) has FD A $\rightarrow$ B. Does relation R and M have equivalent FD ?
asked May 2 in Databases ascend 11 points 7 views
0 votes
0 answers 15 views
Made Easy Book on DBMS, Geeks for Geeks
So recently I have been studying minimization of ER diagrams and have come across a big confusion. So if 2 entities, E1 and E2 are related to each other with one to one cardinality and E1 has Total participation and E2 has Partial participation, ... is 1, but some sources also say that answer should be 2. Also for GATE exam which one should be considered ?
So recently I have been studying minimization of ER diagrams and have come across a big confusion. So if 2 entities, E1 and E2 are related to each other with one to one cardinality and E1 has Total participation and E2 has Partial participation, How many minimum tables will ... the answer is 1, but some sources also say that answer should be 2. Also for GATE exam which one should be considered ?
asked Apr 25 in Databases Palash0007 5 points 15 views
0 votes
1 answer 28 views
Previous year question paper
Consider the following set of Functional dependencies for relational schema R{A,B,C} F={A->BC, B->C, A->B, AB->C} (i) Find the key of relation R
Consider the following set of Functional dependencies for relational schema R{A,B,C} F={A->BC, B->C, A->B, AB->C} (i) Find the key of relation R
answered Apr 25 in Databases zimgateoverflow 5 points 28 views
0 votes
0 answers 20 views
Gate pyq cse
Why in this question use B-->A ,A-->C ?
Why in this question use B-->A ,A-->C ?
asked Apr 23 in Databases Enolx.21 53 points 20 views
0 votes
0 answers 6 views
B+ tree right replication policy
What is right replication policy in database? And how is it different from right biasing?
What is right replication policy in database? And how is it different from right biasing?
asked Apr 19 in Databases dragonball 12 points 6 views
0 votes
1 answer 28 views
self doubt database management system
is it true that “every strict schedule is cascadeless schedule”?
is it true that “every strict schedule is cascadeless schedule”?
answered Apr 17 in Databases Konan-kun 71 points 28 views
0 votes
0 answers 21 views
Self doubt repost
Check for recoverable ,cascadeless & strict.
Check for recoverable ,cascadeless & strict.
asked Apr 15 in Databases rishabhgupta12 11 points 21 views
0 votes
0 answers 9 views
#self doubts
In Database normalization, I had a question. In the 3rd Normal form, we remove the transitive dependency, so due to this removal, we remove some of the redundant entries. My question is why we need BCNF. How re are removing more redundant entries by using BCNF. please explain this by using an example and compare with 3rd normal form.
In Database normalization, I had a question. In the 3rd Normal form, we remove the transitive dependency, so due to this removal, we remove some of the redundant entries. My question is why we need BCNF. How re are removing more redundant entries by using BCNF. please explain this by using an example and compare with 3rd normal form.
asked Mar 27 in Databases Raj_81 23 points 9 views
0 votes
0 answers 35 views
Applied Gate CSE DBMS Subject Test
Relation R (A,B,C,D) with FD'S { A->B, B->C, C->D, D->A } then relation R is decomposed into two relations R1 and R2 such that it is satisfying second normal form, third normal form and BCNF and decomposition is lossy. Then how the attributes are distributed in these two decomposed relations R1 and R2? Note: U is the set of all attributes. 1. 2. 3. 4.
Relation R (A,B,C,D) with FD'S { A->B, B->C, C->D, D->A } then relation R is decomposed into two relations R1 and R2 such that it is satisfying second normal form, third normal form and BCNF and decomposition is lossy. Then how the attributes are distributed in these two decomposed relations R1 and R2? Note: U is the set of all attributes. 1. 2. 3. 4.
asked Mar 14 in Databases samir757 29 points 35 views
1 vote
1 answer 24 views
Self Doubt regarding ER diagram
What is degree of Self Referential Relationship? Unary or Binary?
What is degree of Self Referential Relationship? Unary or Binary?
answered Mar 12 in Databases holla 5 points 24 views
0 votes
0 answers 13 views
Applied Course GATE CS - DBMS Practice test 3
Given 3 T1, T2 and T3 transactions which have (2,2), (3,2), (4,2) read and write operations respectively the no of schedules possible using these three transactions are A. 1260 B. 630630 C. 6 D. 63000
Given 3 T1, T2 and T3 transactions which have (2,2), (3,2), (4,2) read and write operations respectively the no of schedules possible using these three transactions are A. 1260 B. 630630 C. 6 D. 63000
asked Mar 9 in Databases samir757 29 points 13 views
3 votes
3 answers 59 views
Made easy self dought
Q. R(A,B,C,D,E,F) with {A,BC,CD} candidate keys.How many super keys possible?
Q. R(A,B,C,D,E,F) with {A,BC,CD} candidate keys.How many super keys possible?
answered Mar 6 in Databases Devhaan 5 points 59 views
0 votes
0 answers 82 views
Past exam paper MSU 2020 Advanced databases
Given the following relations and SQL query: Student (sid, name, age, address, date of birth, level) Book(bid, title, author) Checkout(sid, bid, date_borrowed, date_returned) SELECT S.sid, S.level, C.date_borrowed, C.date_returned FROM Student ... query using a Relation Connection Graph.[5 marks] d) Represent the query above using a query tree. [5 marks]
Given the following relations and SQL query: Student (sid, name, age, address, date of birth, level) Book(bid, title, author) Checkout(sid, bid, date_borrowed, date_returned) SELECT S.sid, S.level, C.date_borrowed, C.date_returned FROM Student S, Book B, Checkout C ... correctness of the query using a Relation Connection Graph.[5 marks] d) Represent the query above using a query tree. [5 marks]
asked Mar 6 in Databases Drackelyone 5 points 82 views
0 votes
0 answers 32 views
Gate Applied test series
asked Mar 3 in Databases Love Barot 7 points 32 views
0 votes
0 answers 20 views
Data base management system
Hello sir/mam, Today I've been told by our sir that we can write into ROM. Is that specified for mobile ROM or Computer ones or none of them please do clarify my doubt!
Hello sir/mam, Today I've been told by our sir that we can write into ROM. Is that specified for mobile ROM or Computer ones or none of them please do clarify my doubt!
asked Feb 27 in Databases Sai Manognya 5 points 20 views
0 votes
0 answers 14 views
How to convert this problem statement to ER model
Can Somebody know how to design ER Diagram from this ?
Can Somebody know how to design ER Diagram from this ?
asked Feb 21 in Databases ghostman23111 5 points 14 views
4 votes
4 answers 956 views
GATE CSE 2021 Set 2 | Question: 6 | Video Solution
Consider the following statements $S1$ and $S2$ about the relational data model: $S1$: A relation scheme can have at most one foreign key. $S2$: A foreign key in a relation scheme $R$ cannot be used to refer to tuples of $R.$ Which one of the following choices is correct? Both $S1$ and $S2$ are true $S1$ is true and $S2$ is false $S1$ is false and $S2$ is true Both $S1$ and $S2$ are false
asked Feb 18 in Databases Arjun 257 points 956 views
1 vote
2 answers 556 views
GATE CSE 2021 Set 2 | Question: 31 | Video Solution
The relation scheme given below is used to store information about the employees of a company, where $\textsf{empId}$ is the key and $\textsf{deptId}$ indicates the department to which the employee is assigned. Each employee is assigned to exactly ... than the average salary of employees in the department employees in the company female employees in the department female employees in the company
asked Feb 18 in Databases Arjun 257 points 556 views
0 votes
2 answers 704 views
GATE CSE 2021 Set 2 | Question: 32 | Video Solution
Let $S$ be the following schedule of operations of three transactions $T_1$, $T_2$ and $T_3$ in a relational database system: $R_2(Y), R_1(X), R_3(Z), R_1(Y)W_1(X), R_2(Z), W_2(Y), R_3(X), W_3(Z)$ Consider the statements $P$ and $Q$ below: $P$: $S$ is conflict- ... correct? Both $P$ and $Q$ are true $P$ is true and $Q$ is false $P$ is false and $Q$ is true Both $P$ and $Q$ are false
asked Feb 18 in Databases Arjun 257 points 704 views
0 votes
1 answer 611 views
GATE CSE 2021 Set 2 | Question: 40 | Video Solution
Suppose the following functional dependencies hold on a relation $U$ with attributes $P,Q,R,S$, and $T$: $P \rightarrow QR$ $RS \rightarrow T$ Which of the following functional dependencies can be inferred from the above functional dependencies? $PS \rightarrow T$ $R \rightarrow T$ $P \rightarrow R$ $PS \rightarrow Q$
asked Feb 18 in Databases Arjun 257 points 611 views
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