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Recent questions and answers in Databases

1 vote
3 answers
1
What is the maximum number of possible candidate key for relation on n attributes.
answered 4 hours ago in Databases Shashank Rustagi 1k views
0 votes
1 answer
2
Given relation catalog(sid, pid, cost) Find pairs of sids such that the supplier with the first sid charges more for some part than the supplier with the second sid what is the relational algebra expression for this?
answered 6 days ago in Databases Shashwat Pandey 152 views
0 votes
1 answer
3
E and F are multivalued attributes. How many minimum tables which satisfy 1NF ? How many minimum tables which satisfy 2NF ? How many minimum tables which satisfy 3NF ? How many minimum tables which satisfy BCNF ?
answered Oct 21 in Databases 14ash 274 views
2 votes
3 answers
4
1 vote
5 answers
5
2 votes
1 answer
6
I am getting 6,6 as answer but actual answer if 5,6 .Please help P.S:-Appologies for image quality,but this this best i have managed:)
answered Oct 19 in Databases Dhruvil 218 views
0 votes
1 answer
7
Consider the following relational schema for a library: member(memb_no, name, dob) books(isbn, title, authors, publisher) borrowed(memb_no, isbn, date) Write the following queries in relational algebra. a. Find the names of members who have borrowed any book published by ... into account that if a member does not borrow any books, then that member does not appear in the borrowed relation at all.
answered Oct 16 in Databases Tharunsai 404 views
1 vote
1 answer
8
Consider the following locking protocol: I. Transaction must lock all data items before begins any read or write operation. II. Transaction executes all read and write operations alongwith transaction commit. III. Transaction unlocks all data items ... no deadlock, guaranteed serializability and strict recoverability. D Guaranteed serializable and no deadlocks and may not strict recoverabl
answered Oct 13 in Databases ajay05908 121 views
0 votes
2 answers
10
24 votes
3 answers
11
An instance of a relational scheme $R(A, B, C)$ has distinct values for attribute $A$. Can you conclude that $A$ is a candidate key for $R$?
answered Oct 9 in Databases avinash99515 2.9k views
0 votes
1 answer
12
How to create relation tables for a Recursive Relationship set ? Is it same way as any other relationship set ?
answered Oct 8 in Databases Vishal_kumar98 102 views
1 vote
2 answers
13
Relation R which satisfy 3NF and atmost one compound candidate key is also in BCNF (pls explain give counter examples for both true and false)
answered Oct 8 in Databases Shivani Toshniwal 425 views
1 vote
1 answer
14
0 votes
3 answers
15
A primary key, if combined with a foreign key creates parent child relationship between the tables that connect them many-to-many relationship between the tables that connect them network model between the tables that connect them none of these
asked Apr 2 in Databases Lakshman Patel RJIT 266 views
0 votes
1 answer
16
0 votes
1 answer
17
Consider the schema $R=(\text{S T U V})$ and the dependencies $ S \rightarrow T, T \rightarrow U, U \rightarrow V$, and $V \rightarrow S.$ If $R=(R1 \text{ and } R2)$ be a decomposition such that $R1 \cap R2= \phi$ then decomposition is not in $\text{2 NF}$ in $\text{2 NF}$ but not in $\text{3 NF}$ in $\text{3 NF}$ but not in $\text{2 NF}$ in both $\text{2 NF}$ and $\text{3 NF}$
asked Apr 2 in Databases Lakshman Patel RJIT 75 views
0 votes
2 answers
18
Assume transaction $A$ holds a shared lock $R.$ If transaction $B$ also requests for a shared lock on $R.$ It will result in deadlock situation immediately be granted immediately be rejected be granted as soon as it is released by $A$
asked Apr 1 in Databases Lakshman Patel RJIT 172 views
0 votes
1 answer
19
Given relations $R(w,x)$ and $S(y,z),$ the result of SELECT DISTINCT $w,x$ from $R,S$ $R$ has no duplicates and $S$ is non-empty $R$ and $S$ have no duplicates $S$ has no duplicates and $R$ is non-empty $R$ and $S$ has the same number of tuples
asked Apr 1 in Databases Lakshman Patel RJIT 135 views
1 vote
2 answers
20
For a database relation $R(a,b,c,d)$ where the domains of $a,b,c$ and $d$ include only atomic values, only the following functional dependencies and those that can be inferred from them hold. $a \rightarrow c$ $b \rightarrow d$ The relation is in First normal form but not in second normal form Second normal form but not in third normal form Third normal form None of the above
asked Apr 1 in Databases Lakshman Patel RJIT 131 views
1 vote
1 answer
21
0 votes
1 answer
22
When transaction $Ti$ requests a data item currently held by $Tj,Ti$ is allowed to wait only if it has a time stamp smaller than that of $Tj$ (that is $Ti$ is order than Tj). Otherwise, $Ti$ is rolled back (dies). This is Wait-die Wait-wound Wound-wait Wait
asked Apr 1 in Databases Lakshman Patel RJIT 110 views
0 votes
2 answers
23
When transaction $Ti$ requests a data item currently held by $Tj,Ti$ is allowed to wait only if it has a timestamp smaller than that of $Tj$ (that is $Ti$ is order than Tj). Otherwise, $Ti$ is rolled back (dies). This is Wait-die Wait-wound Wound-wait Wait
asked Apr 1 in Databases Lakshman Patel RJIT 105 views
0 votes
0 answers
24
Given relations $R(w,x)$ and $S(y,z),$ the result of SELECT DISTINCT $w,x$ from $R,S$ $R$ has no duplicates and $S$ is non-empty $R$ and $S$ have no duplicates $S$ has no duplicates and $R$ is non-empty $R$ and $S$ has the same number of tuples
asked Apr 1 in Databases Lakshman Patel RJIT 78 views
0 votes
1 answer
27
Assume transaction $A$ holds a shared lock $R.$ If transaction $B$ also requests for a shared lock on $R.$ It will result in deadlock situation immediately be granted immediately be rejected be granted as soon as it is released by $A$
asked Apr 1 in Databases Lakshman Patel RJIT 80 views
0 votes
1 answer
28
Table employees has $10$ records. It has a non-NULL SALARY column which is also UNIQUE. The SQL statement SELECT COUNT(*) FROM EMPLOYEE WHERE SALARY > ALL (SELECT SALARY FROM EMPLOYEE); $10$ $9$ $5$ $0$
asked Apr 1 in Databases Lakshman Patel RJIT 107 views
1 vote
1 answer
29
0 votes
1 answer
30
1 vote
1 answer
32
The employee salary should not be greater than Rs.$2000$. This is integrity constraint. referential constraint. over-defined constraint. feasible constraint.
asked Mar 31 in Databases Lakshman Patel RJIT 321 views
0 votes
1 answer
33
The relational algebra expression equivalent to the tuple calculus expression $\{t\mid t ​ \in ​ r \land (t[A]=10 \land t[B]=20)\}$ is $\sigma_{(A=10\:\lor\:B=20)}(r)$ $\sigma_{(A=10)}(r)\cup\sigma_{(B=20)}(r)$ $\sigma_{(A=10)}(r)\cap\sigma_{(B=20)}(r)$ $\sigma_{(A=10)}(r)-\sigma_{(B=20)}(r)$
asked Mar 31 in Databases Lakshman Patel RJIT 156 views
1 vote
2 answers
34
Let $R=(A,B,C,D,E,F)$ be a relation scheme with the following dependencies: $C\to F,E\to a,EC\to D, A\to B$. Which of the following is a key for $R$? $CD$ $EC$ $AE$ $AC$
asked Mar 31 in Databases Lakshman Patel RJIT 179 views
0 votes
2 answers
35
For a database relation $R(a,b,c,d)$ where the domains of $a,b,c,d$ include only atomic values, only the following functional dependencies and those that can be inferred from them hold: $a\to c\\b\to d$ the relation is in first normal form but not in second normal form. second normal form but not in third normal form. third normal form. none of these.
asked Mar 31 in Databases Lakshman Patel RJIT 183 views
0 votes
1 answer
36
0 votes
2 answers
37
0 votes
1 answer
38
In functional dependency between two sets of attribute $A$ and $B$ then set of attributes $A$ of database is classified as: top right side down left side left hand side right hand side
asked Mar 31 in Databases Lakshman Patel RJIT 157 views
0 votes
1 answer
39
Which type of Statement can execute parameterized queries? PreparedStatement ParameterizedStatement ParameterizedStatement and CallableStatement All kinds of Statements
asked Mar 31 in Databases Lakshman Patel RJIT 249 views
0 votes
1 answer
40
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