Recent questions and answers in Databases - GATE CSE Doubts

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#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.

asked Mar 27 in Databases by Raj_81 (23 points) | 4 views

+1 vote

1 answer

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.

answered Mar 15 in Databases by Dimpi779 (5 points) | 26 views

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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.

asked Mar 14 in Databases by samir757 (17 points) | 23 views

+1 vote

1 answer

Self Doubt regarding ER diagram
What is degree of Self Referential Relationship? Unary or Binary?

answered Mar 12 in Databases by holla (5 points) | 18 views

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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

asked Mar 9 in Databases by samir757 (17 points) | 10 views

+3 votes

3 answers

Made easy self dought
Q. R(A,B,C,D,E,F) with {A,BC,CD} candidate keys.How many super keys possible?

answered Mar 6 in Databases by Devhaan (5 points) | 54 views

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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]

asked Mar 6 in Databases by Drackelyone (5 points) | 70 views

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Gate Applied test series

asked Mar 3 in Databases by Love Barot (7 points) | 23 views

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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!

asked Feb 27 in Databases by Sai Manognya (5 points) | 14 views

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How to convert this problem statement to ER model
Can Somebody know how to design ER Diagram from this ?

asked Feb 21 in Databases by ghostman23111 (5 points) | 10 views

+1 vote

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Gate 2020 question
Consider a database implemented using B+ tree for file indexing and installed on a disk drive with block size of 4 KB. The size of search key is 12 bytes and the size of tree/disk pointer is 8 bytes. Assume that the database has one million ... each record fits into one disk block. The minimum number of disk accesses required to retrieve any record in the database is ______.

asked Feb 13 in Databases by Enolx.21 (49 points) | 19 views

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Made easy test
In this question, it is asked to retrieve the name of each employee who has a dependent with the same first name and is the same sex as employee. How Q1 will give the correct result, coz inside IN() the condition Essn=D,Essn is not there. Can anybody explain.

asked Feb 6 in Databases by Ankita87077 (11 points) | 23 views

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Tga test series
Why dirty read ? Here T2 was commited after the T1....what about the option c?

asked Feb 5 in Databases by Enolx.21 (49 points) | 12 views

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Made easy test series
Consider the following table: A B C a1 b1 c1 a1 b1 c2 a2 b1 c1 a2 b1 c3 Number of non-trivial functional dependencies exists in the above Table ___________.

asked Feb 4 in Databases by vikashrajpoot0100 (5 points) | 22 views

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1 answer

Tga test series

answered Feb 2 in Databases by Parth27 (163 points) | 30 views

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self doubt Databases : What do partial dependencies really mean ?

asked Feb 2 in Databases by ashutoshbsathe (5 points) | 15 views

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Self Doubt , Databases
Is Read – Write conflict possible in a strict recoverable schedule? As strict 2PL guarantees strict recoverable. Is Read-Write conflict possible in a strict recoverable schedule ?

asked Jan 24 in Databases by anurags228 (23 points) | 8 views

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#made-easy #databases
1) 2) 3) 4) ANS GIVEN IS 1 WHY 3 NOT POSSIBLE?

asked Jan 23 in Databases by 404 found (37 points) | 16 views

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Ace Test Series
In this functional dependency there is no transitive dependency so it will be in 3 NF but it has partial dependency. So whether it will be 2 NF or not. As 3NF must be in 2NF. This is MSQ.

asked Jan 19 in Databases by Diya07 (5 points) | 22 views

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Cascade Rollback and Not recoverable at the same time

asked Jan 18 in Databases by reboot (5 points) | 9 views

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Gatebook Mock Test
Assume at Kth level (assuming the level of root as level 1) we strictly exceed 400 then answer will be K-1 and If at Kth level, total number of keys =400 then answer K. Hence, At Root level : 1 Node, 1 Key, 2 Pointers At next level(2nd level) : 2 ... we can have only 160 keys .So to have 400 keys with maximum levels we need the 6th level. Can anyone help me where I am wrong.

asked Jan 18 in Databases by badman (9 points) | 15 views

+1 vote

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DATABASE GFG QUESTION
Consider the following relations A, B, C. How many tuples does the result of the following relational algebra expression contain? Assume that the schema of A U B is the same as that of A. Table A Id Name Age ---------------- 12 Arun 60 15 Shreya 24 99 Rohit 11 ... Rohit 11 Table C Id Phone Area ----------------- 10 2200 02 99 2100 01 How many tuples will be returned by ?

asked Jan 17 in Databases by donniedarko (39 points) | 27 views

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ACE Chapter 3 Normalization
Consider a relation R(ABCDE) with the following functional dependencies sets. Which of the following below alternative can be decomposed into BCNF without violating dependency preserving? { ABC → DE, DE→ C} { AB→ C , ABD → E , E->D } {ABC->DE , D→ B , E→ C } {ABC → DE , D → EA , A → D}

asked Jan 17 in Databases by Surya_Dev Chaturvedi (5 points) | 23 views

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https://gateoverflow.in/1789/gate2014-1-22
Given the following statements: S1: A foreign key declaration can always be replaced by an equivalent check assertion in SQL. S2: Given the table R(a,b,c)R(a,b,c) where aa and bb together form the primary key, the following is a valid ... S1 and S2 are FALSE FOREIGN KEY (a) references R) . Does this line mean that it references the first attribute of R?

asked Jan 17 in Databases by Abhilash Behera (5 points) | 9 views

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1 answer

Made Easy Test Series, DBMS, Functional Dependencies

answered Jan 16 in Databases by Abhisheksmile94 (347 points) | 38 views

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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 Jan 15 in Databases by donniedarko (39 points) | 17 views

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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 non-key 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 Jan 15 in Databases by sankalpmittal (41 points) | 10 views

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Made easy test series
how? can u plese draw them?

asked Jan 13 in Databases by Salla shivateja (19 points) | 26 views

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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 Jan 12 in Databases by ashutoshbsathe (5 points) | 25 views

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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 Jan 11 in Databases by Lucifer2440 (5 points) | 11 views

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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 Jan 11 in Databases by Abhisheksmile94 (347 points) | 32 views

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Joins in Relational Algebra (Self Doubt) while reading Elmasri Navathe

asked Jan 10 in Databases by shubhojit1412 (5 points) | 17 views

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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 Jan 10 in Databases by Abhilash Behera (5 points) | 15 views

+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 wait-die method. This should be the right statement. Is it not ?

answered Jan 8 in Databases by ijnuhb (747 points) | 243 views

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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 (347 points) | 35 views

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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 (347 points) | 13 views

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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) | 41 views

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The database system then writes out enough information to disk

asked Jan 7 in Databases by Tara22 (13 points) | 14 views

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Gate applied course
If an E-R model says E having at least one multi-valued 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) | 28 views

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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) | 20 views

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