Recent questions and answers in Databases - GATE CSE Doubts

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declare an integrity constraint
The text belo is from C J date's database book . Why it would be unreasonable to declare an integrity constraint to that effect ? Correctness: By definition, the database is always at least in a consistent state where, following ... assume that transactions are correct, in the sense that they faithfully reflect just those real-world operations they are supposed to.

asked 11 hours ago in Databases by Tara22 (6 points) | 3 views

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Dbms self doubt
Given the statement- View Serializable testing conditions are both necessary and sufficient conditions for serializability testing", whether it is correct or not? please explain.

asked 12 hours ago in Databases by SuvasishDutta (166 points) | 15 views

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Self doubt : Applied Test DBMS
Question. Given: serach key = 9 bytes, Record pointer = 6bytes Block pointer = 5 bytes, Block size = 512 bytes Every block is 69% full . My Approach: 5n + (9+6)(n-1) <= 69% *(512) 5n + 15n - 15 <= 353.28 20n <= 368.28 n <= 18.41 n = 18. n is order if B tree. keys per node = n-1= 17.

asked 1 day ago in Databases by tp21 (267 points) | 20 views

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Applied course mock test locking protocols

asked 1 day ago in Databases by Vignaneswarkrishna (12 points) | 7 views

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Made Easy test series dbms maximum number of candidate key

asked 1 day ago in Databases by Ram Swaroop (164 points) | 12 views

+2 votes

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Made easy test series : Normalization
if every candidate key of R is simple candidate key and no non trivial functional dependency like non-prime attribute-->other non-prime attribute exists then R also in BCNF. Whether the above given statement is true or false?

answered 1 day ago in Databases by tp21 (267 points) | 39 views

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ISRO 2020 Database
If every non-key attribute functionally dependant on the primary key, then the relation will be in (a) First normal form (b) Second normal form (c) Third normal form (d) Fourth normal form

answered 2 days ago in Databases by vivek07 (9 points) | 33 views

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Self Doubt Transactions DBMS
Explain too.

asked 2 days ago in Databases by kashyap02 (12 points) | 16 views

+1 vote

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Self Doubt: Min no of tables in recursive(unary) relationships

asked 2 days ago in Databases by Sambhrant Maurya (341 points) | 6 views

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Made easy test series : SQL
Consider the following relations: Which of the following query gives suppliers names who have submitted at least one Harvest' brand item? (sno in item is the foreign key referencing sno in supplier). I. Select sname FROM Supplier S, Item t where t.brand ... S where sno IN (Select sno FROM Item where brand = Harvest') What will be the correct answer for above question?

answered 3 days ago in Databases by godfather (9 points) | 14 views

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Self doubt : Serializability Dbms
We know that a schedule even if it is not conflict nor view serializable still it can be consistent and there is no typical method to find them. So my doubt is that Such schedules which are neither view serializable nor conflict serializable but consistent can be termed as serializable??

asked 3 days ago in Databases by Chirag Shilwant (167 points) | 38 views

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applied gate:b-tree

asked 3 days ago in Databases by abhinav649 (65 points) | 6 views

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applied gate mock:dbms
given the SQL quey: SELECT * FROM A WHERE A.T1 NOT IN (SELECT B.T3 FROM B) Number of tuples returned by the above SQL query is:

asked 4 days ago in Databases by abhinav649 (65 points) | 23 views

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GATE MOCK TEST 3 GATE 2019 Q32 DBMS
Is there any trickfor solving such questions quickly. It wasted a lot of time still I couldn’t get it right

asked 4 days ago in Databases by DukeThunders (409 points) | 15 views

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#Self_doubt#Database_NaturalJoin
After doing R natural join S the table will have A,B,C attributes so on natural join of this table with Table T do we need to compare A and C both or only A or C?

asked 6 days ago in Databases by nandani17 (29 points) | 8 views

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MadeEasyTest
I think answer should be 13 (17-4=13) anyone plz confirm

asked 6 days ago in Databases by nandani17 (29 points) | 14 views

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ace testseries full length test
53.

asked 6 days ago in Databases by Rahul Burman (21 points) | 13 views

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Self Doubt: Adding attributes/relations to BCNF to convert it into dependency preserving

asked 6 days ago in Databases by shashin (1.3k points) | 16 views

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Self Doubt: Previous GO DBMS
Query 1 is right and query 2 is wrong right? Query 2 returns SID who has NOT supplied every red part right?

asked Jan 16 in Databases by Debapaul (642 points) | 13 views

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SELF DOUBT: TAKEN FROM GO
Consider that the relation has only one attribute $A$.

asked Jan 16 in Databases by Debapaul (642 points) | 44 views

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RELATIONAL ALGEBRA: SELF DOUBT
If $D_1 , D_2 …. D_n$ are domains in relational model then the relation is a table, which is subset of $D_1 \oplus D_2\oplus...D_n$ $D_1\times D_2 \times...D_n$ $D_1\cap D_2 \cap...D_n$ $D_1\cup D_2 \cup...D_n$

answered Jan 16 in Databases by shashin (1.3k points) | 15 views

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Made Easy Test Series -DBMS
Now given an instance of a schema we cant conclude whether A functionally determines B for the entire relation itself as $A\rightarrow B$ holds for this instance, but it might not hold for the entire schema. But we can conclude this for sure that B doesn’t functionally determine C. So the given 2 statements are not correct. Am I, right?

answered Jan 16 in Databases by shashin (1.3k points) | 8 views

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Doubt on Loop join
https://gateoverflow.in/295638/nested-loop-join Please provide the answer to this question and also what if index would have given in this https://gateoverflow.in/154100/nested-loop-jooin question Please help me in clearing this .

asked Jan 16 in Databases by vijay kumar 2 (29 points) | 8 views

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Made Easy Test Series -DBMS
Now given an instance of a schema we cant conclude whether A functionally determines B for the entire relation itself as $A\rightarrow B$ holds for this instance, but it might not hold for the entire schema. But we can conclude this for sure that B doesn’t functionally determine C. So the given 2 statements are not correct. Am I, right?

asked Jan 16 in Databases by Rishav_Bhatt (13 points) | 3 views

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1 answer

ACE TEST SERIES MOCK TEST

answered Jan 15 in Databases by vikas999 (55 points) | 16 views

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1 answer

self doubts ER diagram
can we merge 2 tables with total participation and 1:1 cardinality ratio? this concept was required in question that asks for a minimum no of tables required by giving the er diagrams.

answered Jan 15 in Databases by vikas999 (55 points) | 8 views

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MADE EASY ADVANCE DBMS
This is not conflict serializable, so 1 false This schedule is allowed under Thomas write rule, so view serializable (as thomas write rule gaurantess view serializibility) Not strict , but recoverable So $2$ and $4$ are correct right?

asked Jan 13 in Databases by Debapaul (642 points) | 32 views

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#Self Doubts # Korth-Indexing
Is there any difference between Primary and Clustered Indexing ? Acccording to Korth they are same but in various sources ( youtube videos, gateoverflow answers ) they are mentioned to be different.

asked Jan 12 in Databases by mehulshankhapal (6 points) | 25 views

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MADE EASY ADVANCE LEVEL FLT
Consider the following schedule which involve $3$ $transaction$ $r_1(x),r_2(y),r_3(y),w_1(x),w_3(x),r_2(z),w_1(x)$ Assume that the timestamp for the $3$ transaction is $(5,2,4).$ Which of the following it satisfies? $(BT=BASIC$ $TIME$ $STAMP,$ $TWR=$ $THOMAS$ $WRITE$ $RULE)$ Both BT and TWR Only BT Only TWR None

answered Jan 9 in Databases by Vimal Patel (852 points) | 53 views

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Made easy test series : Relational Algebra
SQL’s aggregation Sum, Avg, Count can not be expressed in relational algebra. Is the above statement TRUE or FALSE?

asked Jan 8 in Databases by vishal burnwal (123 points) | 18 views

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GATE GURU CSE : FLT
According to me ans should be $4$ Is it right?

asked Jan 8 in Databases by Debapaul (642 points) | 14 views

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Self Doubt:BCNF DBMS
Say you are given table like R(A,B,C,D,E,F)= {AB→C, BC → A, AC→ B , B → D , D→ E } Now how will you figure out how many tables are needed to decompose this function in $BCNF?$ Is there any short formula by which we can figure this out ... ; Any help will be highly appreciated, specially if there is some $formula$ by which we can do it within some seconds or such. Thank you.. :)

asked Jan 5 in Databases by Debapaul (642 points) | 16 views

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MadeEasyFULL SYLLABUS TEST-5 (ADVANCE LEVEL) GATE 2020 Q62 BCNF

asked Jan 5 in Databases by DukeThunders (409 points) | 15 views

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GO DOUBT: Previous
Consider the following statements. If relation R is in 3NF and every key is simple, then R is in BCNF If relation R is in 3NF and R has only one key, then R is in BCNF Both 1 and 2 are true 1 is true but 2 is false 1 is false and 2 is true Both 1 and 2 are false

asked Jan 5 in Databases by Debapaul (642 points) | 21 views

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ace test series dbms sql relational algebra
Q.

asked Jan 5 in Databases by Rahul Burman (21 points) | 15 views

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Applied course test series : Transactions serializability

asked Jan 3 in Databases by vishal burnwal (123 points) | 86 views

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Ace 2019 Mock 3 Q59
please explain ISA relationship and answer

asked Jan 3 in Databases by ssap09 (42 points) | 10 views

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#SelfDoubt#ERDiagram
The answer is D. My question is why C is true as Plz help

asked Jan 3 in Databases by nandani17 (29 points) | 7 views

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1 answer

Applied course test series : SQL
Can someone tell the answer for above question.

answered Jan 2 in Databases by Vimal Patel (852 points) | 21 views

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Applied course test series : ER diagram Concept
Consider the following E-R Diagram What is the minimum no. of relations required for above E-R Diagram? Can someone tell the answer.

asked Jan 2 in Databases by vishal burnwal (123 points) | 23 views

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