Recent questions tagged databases / GATE Overflow for GATE CSE

3 votes

1 answer

31

GO Classes Test Series 2024 | Mock GATE | Test 13 | Question: 31
Let $\text{R}_1, \text{R}_2, \ldots,\text{ }R_n$ be a decomposition of schema $\text{U}$. Let $u(\text{U})$ be a relation, and let $r_i=\Pi_{\text{R}_i}(u)$ ... $u=r_1 \bowtie r_2 \bowtie r_3 \bowtie r_4 \bowtie . . r_n$ None of the above

Let $\text{R}_1, \text{R}_2, \ldots,\text{ }R_n$ be a decomposition of schema $\text{U}$. Let $u(\text{U})$ be a relation, and let $r_i=\Pi_{\text{R}_i}(u)$Which of the f...

GO Classes

399 views

GO Classes asked Jan 28

3 votes

1 answer

32

GO Classes Test Series 2024 | Mock GATE | Test 13 | Question: 32
The order of a leaf node in a $\text{B tree}$ is the maximum number of (value, data record pointer) pairs it can hold. Given that the block size is $1 \mathrm{~K}$ bytes, data record pointer is $7$ bytes long, the value field is $9$ bytes long and a block pointer is $6$ bytes long, what is the order of the leaf node?

The order of a leaf node in a $\text{B tree}$ is the maximum number of (value, data record pointer) pairs it can hold. Given that the block size is $1 \mathrm{~K}$ bytes,...

GO Classes

480 views

GO Classes asked Jan 28

3 votes

1 answer

33

GO Classes Test Series 2024 | Mock GATE | Test 13 | Question: 33
Consider the following two schedules consisting to two transaction $\mathrm{T}_1$ and $\mathrm{T}_2$ : Which of the following is/are true about these schedules? Both $\mathrm{S}_1$ and $\mathrm{S}_2$ are ... and also conflict serializable. $\mathrm{S}_1$ and $\mathrm{S}_2$ are neither conflict equivalent nor conflict serializable.

Consider the following two schedules consisting to two transaction $\mathrm{T}_1$ and $\mathrm{T}_2$ :Which of the following is/are true about these schedules?Both $\math...

GO Classes

281 views

GO Classes asked Jan 28

5 votes

1 answer

34

GO Classes Test Series 2024 | Mock GATE | Test 13 | Question: 64
Consider the following schema: The primary key fields are underlined, and the domain of each field is listed after the field name. Assume there are no NULL values in any column of any relation and every relation has at least one tuple. ... who have a rating of $10 $ OR have reserved boat $104.$ All sids of sailor table Empty set.

Consider the following schema:The primary key fields are underlined, and the domain of each field is listed after the field name. Assume there are no NULL values in any c...

GO Classes

487 views

GO Classes asked Jan 28

3 votes

2 answers

35

GO Classes Test Series 2024 | Mock GATE | Test 13 | Question: 65
Let $r(X, Y)$ and $s(Y)$ be two relations. What is returned by the following relational algebra query? Values of $r.X$ which are related to every value of $s.Y$. Values of $r.Y$ which are related to every value of $s.Y$. ... which are not related to some value of $s.Y$. Values of $r.X$ which are not related to any value of $s.Y$.

Let $r(X, Y)$ and $s(Y)$ be two relations.What is returned by the following relational algebra query?Values of $r.X$ which are related to every value of $s.Y$.Values of $...

GO Classes

498 views

GO Classes asked Jan 28

0 votes

1 answer

36

please explain this sql question and how do we get the answer?

pcla

156 views

pcla asked Jan 27

3 votes

2 answers

37

GO Classes Test Series 2024 | Mock GATE | Test 12 | Question: 23
An attribute $A$ is called prime if $A$ is in any of the candidate keys. Assume in the following statements, $\mathrm{A}$ is an attribute $\&\;\mathcal{X}$ is a set of attributes. Consider the following statements: Domain of each attribute is an ... $\text{A - BCNF, B - 3NF, C - 2NF, D - 1NF}$

An attribute $A$ is called prime if $A$ is in any of the candidate keys. Assume in the following statements, $\mathrm{A}$ is an attribute $\&\;\mathcal{X}$ is a set of at...

GO Classes

453 views

GO Classes asked Jan 21

3 votes

0 answers

38

GO Classes Test Series 2024 | Mock GATE | Test 12 | Question: 24
Assume that a data file has an index consisting of $\text{N}$ items, where $\text{N}$ is large. If a binary search of the index is used to find an item, then, of the following, which best approximates the mean number of comparisons required to locate a ... $\left(\log _2 \text{N}\right)-1$ $\text{N} \log _2 \text{N}$

Assume that a data file has an index consisting of $\text{N}$ items, where $\text{N}$ is large. If a binary search of the index is used to find an item, then, of the foll...

GO Classes

728 views

GO Classes asked Jan 21

12 votes

1 answer

39

GO Classes Test Series 2024 | Mock GATE | Test 12 | Question: 25
Let $\mathrm{R}(\mathrm{a}, \mathrm{b})$ be a schema and $\mathrm{Q} 1$ and $\mathrm{Q} 2$ are queries on $\mathrm{R}$. Q1: SELECT * FROM R; Q2: (SELECT * FROM R) INTERSECT (SELECT * FROM R); Which of the ... to $\text{Q2}$ is always contained in the answer to $\text{Q1}.$ $\text{Q1}$ and $\text{Q2}$ produce different answers.

Let $\mathrm{R}(\mathrm{a}, \mathrm{b})$ be a schema and $\mathrm{Q} 1$ and $\mathrm{Q} 2$ are queries on $\mathrm{R}$.Q1: SELECT * FROM R; Q2: (SELECT * FROM R) INTERSEC...

GO Classes

739 views

GO Classes asked Jan 21

8 votes

2 answers

40

GO Classes Test Series 2024 | Mock GATE | Test 12 | Question: 55
Consider the following partial schedule for several data items for transactions $T_i$ with timestamp $i:$ How many transactions are Aborted by the timestamp scheduler?

Consider the following partial schedule for several data items for transactions $T_i$ with timestamp $i:$ How many transactions are Aborted by the timestamp scheduler?

GO Classes

816 views

GO Classes asked Jan 21

3 votes

0 answers

41

GO Classes Test Series 2024 | Mock GATE | Test 11 | Question: 13
Given the portion of an ER diagram shown above (with a thickened arrow from $R$ to $A),$ which of the following statements are true? $R$ connects each entity in $A$ to at least one entity in $B$ $R$ connects each entity in $A$ to at ... in $B$ to at most one entity in $A$ only I and II only II and III only I and IV only III and IV

Given the portion of an ER diagram shown above (with a thickened arrow from $R$ to $A),$ which of the following statements are true?$R$ connects each entity in $A$ to at ...

GO Classes

635 views

GO Classes asked Jan 13

12 votes

1 answer

42

GO Classes Test Series 2024 | Mock GATE | Test 11 | Question: 57
You are given a table named Alums that contains the names and personal information of all graduates of the college that you work for. It includes name and age attributes, and a state attribute specifying the state in which a person ... of the youngest graduate living in California (CA)? only II only III only I and II only II and III

You are given a table named Alums that contains the names and personal information of all graduates of the college that you work for. It includes name and age attributes,...

GO Classes

899 views

GO Classes asked Jan 13

2 votes

1 answer

43

GO Classes Test Series 2024 | Mock GATE | Test 11 | Question: 58
Consider the following notation for operations of transactions: ... above schedules is/are recoverable? Only $\text{S}_2$ Only $\text{S}_3$ Only $\text{S}_1, \text{S}_3$ None

Consider the following notation for operations of transactions:$$\begin{array}{cl}w_1(A) & \text { transaction } 1 \text { wrote item } A \\r_1(A) & \text { transaction }...

GO Classes

385 views

GO Classes asked Jan 13

4 votes

0 answers

44

GO Classes Test Series 2024 | Mock GATE | Test 11 | Question: 59
Which of the following statements is/are false? In a cascade-less schedule if a transaction $T_j$ read a data item written by transaction $T_i$ then the commit of $T_i$ has to be before this read operation of $T_j$ A ... $2 \mathrm{PL}$ (could have been produced using the $2 \mathrm{PL}$ locking protocol) is conflict-serializable.

Which of the following statements is/are false?In a cascade-less schedule if a transaction $T_j$ read a data item written by transaction $T_i$ then the commit of $T_i$ ha...

GO Classes

451 views

GO Classes asked Jan 13

8 votes

4 answers

45

GO Classes Test Series 2024 | Mock GATE | Test 11 | Question: 60
In a relational database relation, we say a non-empty set of attributes $\mathrm{X}$ is closed (with respect to a given set of functional dependencies FD) if $X^{+}=X$ (where $X^{+}$is the closure of $X).$ ... $2.$ $R$ is in $2 N F$. $R$ is in $3 N F$.

In a relational database relation, we say a non-empty set of attributes $\mathrm{X}$ is closed (with respect to a given set of functional dependencies FD) if $X^{+}=X$ (w...

GO Classes

1.0k views

GO Classes asked Jan 13

0 votes

1 answer

46

Made Easy Test Series
Isn’t F$^{+}$ minimal cover? If C $\rightarrow$ A is already there, then why does augmented CD $\rightarrow$ A needs to be?

Isn’t F$^{+}$ minimal cover? If C $\rightarrow$ A is already there, then why does augmented CD $\rightarrow$ A needs to be?

Mrityudoot

147 views

Mrityudoot asked Jan 12

0 votes

0 answers

47

Topic name:Finding number of Cnadiadte and Super Keys
r=(a1,a2,a3,...a8) assumne that a1a2a3 is a canidate key and other cks we dont know.Then find the number of possible candidate keys and number of superkeys?

r=(a1,a2,a3,...a8) assumne that a1a2a3 is a canidate key and other cks we dont know.Then find the number of possible candidate keys and number of superkeys?

supratikde707

171 views

supratikde707 asked Jan 9

0 votes

1 answer

48

Minimal Cover
In questions asking for the number of FDs in minimal cover if I get say A $\rightarrow$ B A $\rightarrow$ C D $\rightarrow$ EF Then what do I count them as 2 or 3 or 4 FDs?

In questions asking for the number of FDs in minimal cover if I get sayA $\rightarrow$ BA $\rightarrow$ CD $\rightarrow$ EFThen what do I count them as2 or 3 or 4 FDs?

Mrityudoot

238 views

Mrityudoot asked Jan 8

2 votes

2 answers

49

ISRO 2024
Which of the following SQL query deletes all tuples in the teacher relation for those teachers associated with a department located in the building with name CSE and which is in department relation: DELETE FROM teacher WHERE dept_name IN CSE'; DELETE FROM ... WHERE dept_name IN ( SELECT dept_name FROM department WHERE building = CSE); DELETE FROM teacher WHERE dept_name IN CSE';

Which of the following SQL query deletes all tuples in the teacher relation for those teachers associated with a department located in the building with name CSE and whic...

Ramayya

478 views

Ramayya asked Jan 7

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title	title:apple
content	content:apple
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