Recent questions in Databases

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1

Tuple Relational Calculus - What is the difference between these two types of bounded variables in the expressions?

asked 4 days ago in Databases by tarunmaganti (265 points) | 27 views

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2 answers

2

Made easy workbook

asked 6 days ago in Databases by Avik Chowdhury Junior (539 points) | 39 views

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1 answer

3

No of Schedules
Given, Transaction T1 has n operation Transaction T2 has m operation Prove that, the total number of schedules possible is $\frac{(m+n)!}{m!n!}$

asked Apr 13 in Databases by hacker16 Active (2.6k points) | 28 views

–1 vote

1 answer

4

Self Doubt on DBMS
Please tell if this formula is correct: Minimum number of tables for an ER Diagram = Number of Weak Entities + Number of Strong Entities + Number of Composite Attributes + Number of Multivalued attributes + Number of M:N Relationships - (Number of M:N Relationships with total participation on atleast 1 side + Number of non-M:N Relationships with total participation on both sides)

asked Apr 12 in Databases by Balaji Jegan Junior (883 points) | 32 views

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2 answers

5

Indexing
What is the Difference between Primary and Clustering Index or both are actually the Same ?

asked Apr 12 in Databases by Na462 Active (1.6k points) | 46 views

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1 answer

6

Doubt Question
In this Question :- Let there is a Table named Stud_records with 3000 records of fixed length , each record size is 50 Bytes and records are stored in a block of size 512 Bytes , If secondary index is built on the key field of size 10 Bytes and a block pointer of size 5 ... 88 Blocks The number of blocks in First level index = (88 * 15)/512 = 3 ???? Why am i wrong ?? Please Help?

asked Apr 12 in Databases by Na462 Active (1.6k points) | 47 views

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1 answer

7

Dirty Read
Correct me where i am wrong if i am wrong Please :) Dirty Read means Reading the data of uncommited transaction. For removing the Dirty read we should always read after the transaction which wrote X commits , this is the only way to remove dirty read rt ? T1 T2 ... (x) Above Shown is The Only way of removing the Dirty read rt ? My doubt is its very similar to the Solution of Cascadeless.

asked Apr 12 in Databases by Na462 Active (1.6k points) | 24 views

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1 answer

8

ER Diagram to Tables
Please Clear My Doubts here:- 1. In one to one Cardinality if we have Total Participation on One Side or Total Participation on both sides Then only 1 Table is Required. In that table the primary key will be of Entity with total participation.? 2. ... ://gateoverflow.in/143186/minimum-number-of-tables-to-represent-er-diagram How to solve such questions. Plz hep me out here :(

asked Apr 12 in Databases by Na462 Active (1.6k points) | 40 views

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1 answer

9

Normalization-(prime attribute -> prime attribute dependency is there in BCNF)

asked Apr 11 in Databases by srestha Veteran (81.7k points) | 54 views

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0 answers

10

Transaction
how view serializability ensures serial schedule?? i mean in view we leave many conflict like RW,WW,......we only talks about WR conflict and intial read and final write. then how it ensurs serailizability??

asked Apr 10 in Databases by Ravi prakash pandey Junior (743 points) | 13 views

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11

Self doubt
How to calculate super key of any relation? Pls explain with example.

asked Apr 8 in Databases by Dhoomketu (25 points) | 43 views

+2 votes

1 answer

12

Made Easy Online Test Series:Database1 Gate 2019

asked Apr 7 in Databases by Sona Barman Junior (987 points) | 64 views

+1 vote

0 answers

13

ISI sample paper

asked Apr 3 in Databases by shivanisrivarshini Boss (14k points) | 68 views

0 votes

1 answer

14

Normalization

asked Apr 1 in Databases by Sourabh Keshri (73 points) | 42 views

+1 vote

1 answer

15

#dbms
emp(eid,ename,age,salary) works(eid,did,pettime) dept(did,dname,budget,managerid) 1.print the names and salary of each employee who works in more than on department. 2.for each department with 15 or more employees,print the department name and the number ... .find the name and age of managers who manage the departments with the largest budgets,and list the related employees in the department.

asked Mar 29 in Databases by Naveen Nallanti (29 points) | 51 views

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0 answers

16

ER Model
Is every relation in an ER model one to one ?

asked Mar 27 in Databases by prashantt144 (13 points) | 33 views

+1 vote

1 answer

17

test_series
Question on index block access this question similar to https://gateoverflow.in/61557/indexing I think answer must be 300

asked Mar 25 in Databases by mehul vaidya Junior (593 points) | 43 views

+2 votes

1 answer

18

Dependency preserving decompostion
A relation $R(ABCD)$ is given FD set = $\{ AB\rightarrow CD , D\rightarrow A \}$ R1(ABC) R2(AD) R3(BCD) Test Dependencies in R1, R2 ,R3 ? Pls explain the solution in detail.....

asked Mar 25 in Databases by Shubham Sharma 2 Loyal (5.4k points) | 37 views

+1 vote

2 answers

19

test_series
can somebody please answer this ? Number of tables needed for ER diagram I understand about minimum table must be three , but for maximum it must be 5., as best possible normalized table is table with just two attribute, hence we can break E1 as (A11, A12) and (A11 , A13) , even though it is not necessary

asked Mar 25 in Databases by mehul vaidya Junior (593 points) | 35 views

+1 vote

1 answer

20

View serializable
Is this schedule view serializable?

asked Mar 23 in Databases by Mehraj (41 points) | 34 views

0 votes

1 answer

21

DBMS Relational Algebra
Which of the following Queries is more Efficient on the given data? 1. In terms of Space. 2. In terms of Calculation. also, How many calculations are necessary for Each?

asked Mar 20 in Databases by slowpoke (53 points) | 61 views

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22

ISI CSB 2017
Consider the following relational schema: DOCTOR(DoctorName, RegistrationNumber) PATIENT(PatientID, PatientName) ASSIGNED-TO(PatientID, DoctorName). The primary keys for the DOCTOR and PATIENT relations are in bold. Write the tuple relational calculus expression(or an equivalent SQL query) to find the names of all patients who are assigned to more than one doctor.

asked Mar 20 in Databases by shivanisrivarshini Boss (14k points) | 54 views

+1 vote

4 answers

23

Lossy or Lossless
Consider the relation $R(ABCDEG)$ and $FD's$ are $\{AB \rightarrow C,AC \rightarrow B,AD \rightarrow E,B \rightarrow D,BC \rightarrow A,E \rightarrow G\}$ then the decomposition$\{ABC,ACDE,ADG\}$ is lossless and not dependency preserving is not lossless and dependency preserving is lossless and dependency preserving is not lossless and not dependency preserving

asked Mar 19 in Databases by shivanisrivarshini Boss (14k points) | 85 views

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1 answer

24

test_series
why A 3NF table which does not have multiple overlapping candidate keys is said to be in BCNF? https://dba.stackexchange.com/questions/81310/what-exactly-is-overlapping-candidate-key https://gateoverflow.in/150945/normal-form I read above two links , They went bouncer. ... in BCNF because E is not S.K. But how can Overlapping of ABC & ACE stopping this relation from becoming BCNF ?

asked Mar 17 in Databases by mehul vaidya Junior (593 points) | 24 views

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0 answers

25

Database Management Systems by Raghu Ramakrishnan, Johannes Gehrke ~ 2nd edition Q4.3.5

asked Mar 11 in Databases by Aman Janko (15 points) | 70 views

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0 answers

26

doubt
Does KEY for an instance makes sense?What is the benefit of it?

asked Mar 9 in Databases by Angkit Active (3.5k points) | 27 views

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1 answer

27

B+ TREE
What does this sentence mean ? A B+ - tree of order d is a tree in which each internal node has between d and 2d key values.

asked Mar 9 in Databases by hsmart (59 points) | 32 views

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0 answers

28

DBMS question on Join
Consider three relations R1(X, Y, Z), R2(M, N, P ), and R3(N, X). The primary keys of the relations are in Bold. The relations have 100, 30, and 400 tuples, respectively. The space requirements for different attributes are: X = 30 ... of join for the minimum cost. The cost of a join is defined as the total space required by the intermediate relations. Justify your answer.

asked Mar 7 in Databases by Junaed Siddiquee (179 points) | 34 views

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29

Ugc net november 17 paper 3 qno 12

asked Mar 7 in Databases by Meghanain (7 points) | 35 views

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30

Database Management
Suppose we have $20,000$ document collection that has $4,000,000$ total words (including repeats). We want to build an inverted index on this corpus. To keep things simple, we will assume this index is made up dictionary blocks, where a dictionary record ... dictionary to take? How many blocks would you expect the posting list for the $400^{th}$ most common word to take?

asked Mar 6 in Databases by saurabh18 (7 points) | 42 views

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