Questions without a selected answer in Databases

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SandeepKumar147 asked 2 days ago

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B tree dbms

Relational Database
Give an appropriate tree-structure diagram for the following relational database: Employee (person_name, street, city) Works (person_name, company_name, salary) Company (company_name, city) Manages (person_name, manager_name)

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SandeepKumar147 asked 2 days ago

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Give an appropriate tree-structure diagram for the following relational database:Employee (person_name, street, city)Works (person_name, company_name, salary)Company (com...

peter09

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peter09 asked Apr 16

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RBR Normalisation example problem
In on of the examples shown by RBR sir, under Normalization I think he did this problem incorrectly, Given relation R(ABC) and fd: AB->C and C->A, convert it into 2NF For this question, the answer according to RBR sir was that the ... "BC", therefore we need to split the tables into AC and ABC is what my solution. Kindly correct me if I am wrong

In on of the examples shown by RBR sir, under Normalization I think he did this problem incorrectly, Given relation R(ABC) and fd: AB->C and C->A, convert it into 2NFFor ...

nareshit

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nareshit asked Apr 15

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1 answer

Minimal Cover
Consider R(A,B,C,D,E,H) be a relational schema with the following functional dependencies: A->BC, CD->E, E->C, D->AEH, ABH->BD, DH->BC Find minimal cover ?

Consider R(A,B,C,D,E,H) be a relational schema with the following functional dependencies:A->BC, CD->E, E->C, D->AEH, ABH->BD, DH->BCFind minimal cover ?

Yogesh_Jangde

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Yogesh_Jangde asked Apr 13

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If P and Q are predicates and P is the relational algebra expression, then which of the following equivalence are valid ? (1) σP(σQ(e)) = σQ(σP(e)). (2) σP(σQ(e)) = σP ∪ Q(e) (3) σP(σP(e)) = σP V Q (4) All of these

Relation R(A1, A2, A3 ..... An) n attributes. On this relation m simple candidate key (m ≤ n). How many super keys possible in this relation? A. 2m – 1 B. (2n – 1) ⋅ 2n-m C. 2n – 1 D. (2m – 1) 2n-m

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SandeepKumar147 asked Apr 8

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1 answer

Can a candidate key for a composite attribute be called a composite key?
Let's take an example of student entity type Name Class Section Address (Line1, Line2, City, State, Country, PinCode) Since composite attribute holds multiple atomic attributes, such that the group is treated as ... (ignoring the semantics) the combinations like {Class, Section} {Class, Address} {Name, Class, Section}

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SandeepKumar147 asked Apr 5

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Let's take an example of student entity typeNameClassSectionAddress (Line1, Line2, City, State, Country, PinCode)Since composite attribute holds multiple atomic attribute...

tbhaxor

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tbhaxor asked Apr 4

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1 answer

Explain why BCNF is said to be improved 3NF.

PRIYANKA pp PIU

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PRIYANKA pp PIU asked Mar 16

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File organisation and indexing (DBMS)

Suryadip

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Suryadip asked Mar 9

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#TOC

Çșȇ ʛấẗẻ

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Çșȇ ʛấẗẻ asked Feb 24

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#dbms

Çșȇ ʛấẗẻ

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Çșȇ ʛấẗẻ asked Feb 24

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NPTEL DBMS (Introduction to Database systems)course Assignment 10: Topic Database Indexing
Use the following information to answer Questions 7 and 8. A sorted file has the following details: Number of records = 13,10,720; record length = 200 bytes; size of the primary key field = 13 bytes; size of ... of blocks in the first level index file is: a)131072 b)1311 c)1310 d)1286 Accepted Answers: 1286

Use the following information to answer Questions 7 and 8.A sorted file has the following details: Number of records = 13,10,720; record length = 200 bytes;size of the pr...

RishabhSahu325

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RishabhSahu325 asked Feb 22

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2 answers

GATE DS&AI 2024 | Question: 21
Consider the following two tables named Raider and Team in a relational database maintained by a Kabaddi league. The attribute ID in table Team references the primary key of the Raider table, ID. Raider ID Name Raids RaidPoints $1$ Arjun $200$ $250$ $2$ ... Jaipur" AND RaidPoints > 200; The number of rows returned by this query is $\_\_\_\_\_\_\_\_$.

Consider the following two tables named Raider and Team in a relational database maintained by a Kabaddi league. The attribute ID in table Team references the primary key...

GATE DS&AI 2024 | Question: 36
Given the relational schema $R=(U, V, W, X, Y, Z)$ and the set of functional dependencies: \[ \{U \rightarrow V, U \rightarrow W, W X \rightarrow Y, W X \rightarrow Z, V \rightarrow X\} \] Which of the following functional dependencies can be derived from the above set? $V W \rightarrow Y Z$ $W X \rightarrow Y Z$ $V W \rightarrow U$ $V W \rightarrow Y$

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Arjun asked Feb 16

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1 answer

Given the relational schema $R=(U, V, W, X, Y, Z)$ and the set of functional dependencies:\[\{U \rightarrow V, U \rightarrow W, W X \rightarrow Y, W X \...

GATE CSE 2024 | Set 2 | Question: 9
Once the $\text{DBMS}$ informs the user that a transaction has been successfully completed, its effect should persist even if the system crashes before all its changes are reflected on disk. This property is called durability atomicity consistency isolation

894 views

Arjun asked Feb 16

1 votes

2 answers

Once the $\text{DBMS}$ informs the user that a transaction has been successfully completed, its effect should persist even if the system crashes before all...

GATE CSE 2024 | Set 2 | Question: 10
In the context of owner and weak entity sets in the $\text{ER}$ (Entity-Relationship) data model, which one of the following statements is TRUE? The weak entity set MUST have total participation in the identifying ... in the identifying relationship Neither weak entity set nor owner entity set MUST have total participation in the identifying relationship

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Arjun asked Feb 16

1 votes

1 answer

In the context of owner and weak entity sets in the $\text{ER}$ (Entity-Relationship) data model, which one of the following statements is TRUE?The weak entity set MUST h...

GATE CSE 2024 | Set 2 | Question: 16
Which of the following file organizations is/are $\text{I/O}$ efficient for the scan operation in $\text{DBMS}$? Sorted Heap Unclustered tree index Unclustered hash index

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Arjun asked Feb 16

3 votes

2 answers

Which of the following file organizations is/are $\text{I/O}$ efficient for the scan operation in $\text{DBMS}$?SortedHeapUnclustered tree indexUnclustered...

GATE CSE 2024 | Set 2 | Question: 17
Which of the following statements about the Two Phase Locking ($2 \mathrm{PL}$) protocol is/are TRUE? $2 \mathrm{PL}$ permits only serializable schedules With $2 \mathrm{PL}$, a transaction always locks the data item being read or ... , no more locks on any data item can be obtained inside that transaction A deadlock is possible with $2 \mathrm{PL}$

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Arjun asked Feb 16

1 votes

1 answer

Which of the following statements about the Two Phase Locking ($2 \mathrm{PL}$) protocol is/are TRUE?$2 \mathrm{PL}$ permits only serializable schedulesWith $...

GATE CSE 2024 | Set 2 | Question: 35
The relation schema, Person (pid, city), describes the city of residence for every person uniquely identified by pid. The following relational algebra operators are available: selection, projection, cross product, and rename. To find the list of cities ... above operators, the minimum number of cross product operations that must be used is $1$ $2$ $3$ $4$

2.0k views

Arjun asked Feb 16

2 votes

1 answer

The relation schema, Person (pid, city), describes the city of residence for every person uniquely identified by pid. The following relational algebra oper...

GATE CSE 2024 | Set 2 | Question: 46
A functional dependency $F: X \rightarrow Y$ is termed as a useful functional dependency if and only if it satisfies all the following three conditions: $\text{X}$ is not the empty set. $\text{Y}$ is not the empty set. Intersection ... set. For a relation $\text{R}$ with $4$ attributes, the total number of possible useful functional dependencies is __________.

2.3k views

Arjun asked Feb 16

1 votes

1 answer

A functional dependency $F: X \rightarrow Y$ is termed as a useful functional dependency if and only if it satisfies all the following three conditions:$\text{X}$ is not ...

GATE CSE 2024 | Set 1 | Question: 10
Let $\mathrm{S}$ be the specification: "Instructors teach courses. Students register for courses. Courses are allocated classrooms. Instructors guide students." Which one of the following $\mathrm{ER}$ diagrams CORRECTLY represents $\mathrm{S}$? $\text{(i)}$ $\text{(ii)}$ $\text{(iii)}$ $\text{(iv)}$

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Arjun asked Feb 16

1 votes

2 answers

Let $\mathrm{S}$ be the specification: "Instructors teach courses. Students register for courses. Courses are allocated classrooms. Instructors guide students." Which one...

GATE CSE 2024 | Set 1 | Question: 11
In a $\mathrm{B}+$ tree, the requirement of at least half-full $(50 \%)$ node occupancy is relaxed for which one of the following cases? Only the root node All leaf nodes All internal nodes Only the leftmost leaf node

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Arjun asked Feb 16

2 votes

3 answers

In a $\mathrm{B}+$ tree, the requirement of at least half-full $(50 \%)$ node occupancy is relaxed for which one of the following cases?Only the root nodeAll leaf nodesAl...

GATE CSE 2024 | Set 1 | Question: 25
Consider the following two relations, $R(A, B)$ and $S(A, C)$: $R$ $A$ $B$ $10$ $20$ $20$ $30$ $30$ $40$ $30$ $50$ $50$ $95$ $S$ $A$ $C$ $10$ $90$ $30$ $45$ $40$ $80$ The total number of tuples obtained by evaluating the following expression $\sigma_{B<C}\left(R \bowtie_{R . A=S . A} S\right)$ is ___________.

2.3k views

Arjun asked Feb 16

1 votes

1 answer

Consider the following two relations, $R(A, B)$ and $S(A, C)$:$R$$A$$B$$10$$20$$20$$30$$30$$40$$30$$50$$50$$95$$S$$A$$C$$10$$90$$30$$45$$40$$80$The total number of tuples...

GATE CSE 2024 | Set 1 | Question: 34
The symbol $\rightarrow$ indicates functional dependency in the context of a relational database. Which of the following options is/are TRUE? $(X, Y) \rightarrow(Z, W)$ implies $X \rightarrow(Z, W)$ $(X, Y) \rightarrow(Z, W)$ ... $(X, W) \rightarrow Z$ $(X \rightarrow Y$ and $Y \rightarrow Z)$ implies $X \rightarrow Z$

1.8k views

Arjun asked Feb 16

1 votes

3 answers

The symbol $\rightarrow$ indicates functional dependency in the context of a relational database. Which of the following options is/are TRUE?$(X, Y) \rightarrow(Z, W)$...

GATE CSE 2024 | Set 1 | Question: 36
Consider the following read-write schedule $\text{S}$ over three transactions $T_{1}, T_{2}$, and $T_{3}$ ... to $\text{S}$? $T_{1} T_{2} T_{3}$ $T_{1} T_{3} T_{2}$ $T_{3} T_{2} T_{1}$ $T_{3} T_{1} T_{2}$

2.2k views

Arjun asked Feb 16

1 votes

1 answer

Consider the following read-write schedule $\text{S}$ over three transactions $T_{1}, T_{2}$, and $T_{3}$, where the subscripts in the schedule indicate trans...

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 13
Division operator in relational algebra is appropriate to handle which of the following query types? employees work on at most one of the critical projects employees work on any one of the critical projects employees work on at least one of the critical projects employees work on all the critical projects

2.3k views

Arjun asked Feb 16

4 votes

1 answer

Division operator in relational algebra is appropriate to handle which of the following query types?employees work on at most one of the critical projectsemployees work o...

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 14
A B-Tree of order $m$ is an $m$-way search tree. What is the minimum number of keys that can be stored on the leaf level of a B-Tree of order 20 with 3 levels? (Note: the root of a tree counts as its first level)

390 views

GO Classes asked Feb 5

6 votes

3 answers

A B-Tree of order $m$ is an $m$-way search tree. What is the minimum number of keys that can be stored on the leaf level of a B-Tree of order 20 with 3 levels? (Note: th...

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 40
Consider the following schema (primary keys are underlined): Which of the following queries returns the department numbers of those departments for which there are no courses being offered?

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GO Classes asked Feb 5

4 votes

0 answers

Consider the following schema (primary keys are underlined):Which of the following queries returns the department numbers of those departments for which there are no cour...

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 41
Consider the following lock requests in the Table below. And note that: $\mathrm{S}(\cdot)$ and $\mathrm{X}(\cdot)$ stand for 'shared lock' and 'exclusive lock', respectively. $T_1, T_2, T_3, T_4$, and $T_5$ represent five ... dead('-'). Select all that are correct. At t3: a At t6: b At t7: a At t8: -

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GO Classes asked Feb 5

9 votes

1 answer

Consider the following lock requests in the Table below. And note that:$\mathrm{S}(\cdot)$ and $\mathrm{X}(\cdot)$ stand for 'shared lock' and 'exclusive lock', respectiv...