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312
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why are IS and S locks compatible ?
if a node R1 is in IS mode then it may be a possibility that some node below it is in exclusivelock then how can we lock R1 in S mode since if I apply S on it that means ...
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0 0 votes
2 answers 2 answers
779
779 views
how to approach this type of question
i know how to find whether the decomposition is lossless or lossy . but in this type of question they are actually not defining how they decompose . they are only giving ...
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0 0 votes
2 2 answers
854
854 views
How is the below schedule conflict serializable ?
 I am not getting that due to Write(A) in T1 and Read(A) in T2 , I will have an edge from T1 to T2 , and then due to Write(B) in T1 and then Read(B) in T1 , we will have ...
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0 0 answers
490
490 views
How can in the below schedule write write operation can be swapped ?
I am nt getting how this write operation in the first case can be converted into a serial schedule in both the two cases , i.e we are given the first set as the complete ...
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0 0 votes
2 answers 2 answers
5.1k
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Advantage of B+ tree over B tree
I am unable to get that what advantage do we get when we store only records consisting of primary attributes in case of B+ tree i.e. we do not store record pointers corre...
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1 1 answer
14.6k
14.6k views
Consider the relation R(A,B,C,D) with dependencies AB -> C, ABC -> D and AC ->>- B.
R is not in 3NF R is in 3NF but not in BCNF R is in BCNF but not in 4NF R is in 4NF How to approach this ques ?
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1 1 vote
1 answers 1 answer
660
660 views
Canonical cover is in which normal form ?
I am just having one confusion that if we have a canonical cover so it doesn't have any extraneous attributes or redundancy , so is it always in normal form, or not alway...
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1 1 answer
1.1k
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Consider a relational table r with sufficient number of records, having attributes A1, A2,…, An and let 1 <= p <= n.
The database can be configured to do ordered indexing on Ap or hashing on Ap. Which of the following statements is TRUE?(A) Ordered indexing will always outperform hashin...
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1 1 answer
1.4k
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Find out all the books which are either issued, or have been supplied by a supplier.
BOOK (acc_no, year, title)USER (card_no, name, address)SUPPLIER (s_name, address)BORROWED_BY (acc_no, card_no, date of issue)SUPPLIED_BY (acc_no, date of supply, price,...
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0 0 votes
2 2 answers
1.9k
1.9k views
give answer for relational algebra , tuple calculas , and SQL
BOOK(acc_no.,year,title)USER(card_no.,names,address)SUPPLIER(s_name,address)BORROWED BY (acc_no.card_no,date of issue)SUPPLIED BY(acc_no,date of supply,price ,s_name)in a...
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1 1 vote
1 1 answer
862
862 views
why is the below statement regrading weak entity correct ?
Weak entity set avoids the data duplication and consequent possible inconsistencies caused by duplicating the key of the strong entity..plz clarify this........
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1 1 vote
1 1 answer
970
970 views
How to draw E-R model for the below scenario ?
Each employee is assigned to a project work at only one location for that project, but can be at a different location for a different project. At a given location, an emp...
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0 0 votes
1 1 answer
926
926 views
If there are mapping constraints in the E-R diagram , can we reduce the size of the table ?
I am not getting that how many attributes must be there in the Borrowed by table which actually represents a table since we have the constraint that one user can borrow o...
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6 6 votes
3 answers 3 answers
15.1k
15.1k views
Find canonical cover for the given set of functional dependencies.
Consider the following set of functional dependency on the scheme (A, B,C)A&rarr;BC, B&rarr;C, A&rarr;B, AB&rarr;CThe canonical cover for this set is:A. A&rarr;BC and B&r...
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1 1 vote
2 answers 2 answers
2.4k
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database
decompose relation into 2NF ,3NF,BCNFR(ABCDE) {AB ->C, DE ->C , B ->D}R(ABCD) {AB ->C,C >D,D >A}
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1 1 vote
1 answers 1 answer
5.6k
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A relation R(ABCDE) with FD set f = {A -> BC, C -> DE, D -> E} and the decomposition d = { R1(ABCD), R2(DE)}. Is this decomposition dependency preserving?
The answer given is YES. But how is the dependency C - DE preserved in this decomposition?
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3 3 votes
3 3 answers
3.1k
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F = {X -> YZ, Y -> XZ, Z -> X} How many no. of minimal and canonical covers are possible?
Answer is 2 minimal and 2 canonical covers.Please give full explanation of how to solve.
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15 15 votes
4 answers 4 answers
7.0k
7.0k views
solve
How many view equal serial schedules possible for the followingschedule?S : w1(A) r2(A) w3(A) r4(A) w5(A) r6(A) w7(A) r8(A
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0 0 votes
1 1 answer
671
671 views
explain!
Suppose a phone book contain 500 pages and each page can containupto 500 records. Suppose we want to search for a particular name in aphone book. Give a worst case bound ...
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1 1 vote
1 1 answer
602
602 views
database explain
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0 0 votes
2 2 answers
1.9k
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explain
If R and S are two relation in BCNF the natural join of R and S is alsoin BCNF.above statement true or false.??
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0 0 votes
1 answers 1 answer
676
676 views
give statement in english for SQL
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4 4 votes
4 answers 4 answers
11.7k
11.7k views
UGC NET CSE | Junet 2015 | Part 3 | Question: 7
Let $E_1$ and $E_2$ be two entities in E-R diagram with simple single valued attributes. $R_1$ and $R_2$ are two relationships between $E_1$ and $E_2$ where $R_1$ is one-...
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0 0 votes
1 1 answer
1.7k
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write down Domain Relational Calculas query?
employee(person-name,street,city)works(person-name,company-name,salary)company(company-name,city)manages(person-name,manager-name) Find all employees who earn more than e...
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0 0 votes
1 answers 1 answer
859
859 views
Is there any condition in which we can say that dense index is sparse index??
Is there any condition in which we can say that dense index is sparse index?
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0 0 votes
2 2 answers
1.5k
1.5k views
y not a? many time confuse in this kind of questions
Manager’s salary details are hidden from the employee. This is called as(A) Conceptual level data hiding (B) Physical level data hiding (C) External level data hiding (D)...
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1 1 vote
1 1 answer
4.0k
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UGC NET CSE | December 2013 | Part 2 | Question: 11
The student marks should not be greater than 100. This isIntegrity constraintReferential constraintOver-defined constraintFeasible constraint
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13 13 votes
3 3 answers
7.1k
7.1k views
ISRO2015-21
If $\text{D}_1,\text{D}_2, \dots \text{D}_n$ are domains in a relational model, then the relation is a table, which is a subset of$\text{D}_1 \oplus \text{D}_2 \oplus \do...
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1 1 vote
2 answers 2 answers
2.6k
2.6k views
ER MODEL
HOW many minimum relation which satisfy BCNF.??
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4 4 votes
2 answers 2 answers
2.4k
2.4k views
join
Consider a relation $R(A,B,C)$ with the following functional dependencies $AB \to C$ and $AC \to B$. $A$ can take 20 distinct values, $B$ can take 10 distinct values and ...
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