Recent questions in Databases

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1

Entity relationship
Minimum number of tables required and explain how

asked 11 hours ago in Databases by Iamgveeresh (7 points) | 13 views

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1 answer

2

LHS of 3NF and BCNF
Why LHS of a 3NF or BCNF should be a super key and why not just a candidate key?

asked 6 days ago in Databases by felics moses 1 (53 points) | 28 views

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3

Trigger
what is the correct answer?

asked 6 days ago in Databases by hacker16 Active (2.7k points) | 14 views

+1 vote

1 answer

4

Made Easy Doubt 4
Consider a relation r1(A, B, C), r2(C, D, E) and r3(F, G) with primary keys A, C and F respectively. Assume that r1 has 150 tupples, r2 has 100 tupples and r3 has 75 tupples. The number of resultant tuple in are ________.

asked Jun 14 in Databases by Na462 Active (3.3k points) | 54 views

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5

Made Easy Doubt 3
The following key values are inserted into B+ tree in which the order of internal nodes is 4 and that of the leaf node is 5 in the sequence given below. The order of internal node is maximum number of keys in each node and the order of leaf ... responsible of leaf node split up as a result of these insertion is ________. (Assume right baising) Soln. Please Verify my solution :-

asked Jun 14 in Databases by Na462 Active (3.3k points) | 32 views

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6

Made Easy Question 2
Consider relation R' and S' have n' and m' tuples, respectively. Choose the best matching between List-I (Expression) and List-II (Maximum number of tuple): Soln. According to me Answer should be Option C. 1.R union S = m+n (easy nothing to say) 2. Say Relations are like:- R(A ... 3 3 4 2 3 3 3 5 4 3 3 3 6 Now in R natual join S = m * n So option C should suffice isn't it ?

asked Jun 14 in Databases by Na462 Active (3.3k points) | 28 views

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2 answers

7

Made Easy Question 1
Consider The Following Schema:- The minimum number of tables needed to represent E1 , E2and E3 are ______ Soln. According to me Answer should be 2 because We can merge 1. R1 and E2 in one Relation 2. E1,R2,E3 in one because its total participation on both the sides. So total 2 Tables Should be Enough.

asked Jun 14 in Databases by Na462 Active (3.3k points) | 24 views

+1 vote

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8

Doubt
1. Why in question They treat both clustered and primary indices Different, because both are the same thing(written in Korth). Only the thing is Primary indices means search key is Primary Key and Clustered means it can be any search Key and both defines the ... a clustered index and i took another attribute not in the order say Salary and created a different Secondary index on the Records ?

asked Jun 13 in Databases by Na462 Active (3.3k points) | 35 views

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2 answers

9

NORMALIZATION
Given: The Relation R(A,B,C,D,E) having (A,B) as Primary key. The set of functional dependencies: (A,C)-->D , (B,D)-->E. I want to Know whether the functional dependencies Given above are Partial FD's or Not?

asked Jun 8 in Databases by pradeepchaudhary (71 points) | 51 views

+1 vote

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10

Hacker Earth Normalization Question
A particular database is normalized to satisfy a particular level of normalization (either 1NF or 2NF or 3NF). One of the tables contains, among other fields, a column for the City and a column for the Zip Code. Assuming that there is a many-to-one mapping ... , we may conclude that the database is definitely NOT in xNF form. What is the integer x (1, 2, or 3)?

asked Jun 8 in Databases by pradeepchaudhary (71 points) | 65 views

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1 answer

11

File indexing

asked Jun 7 in Databases by Dipanshu Rana (85 points) | 29 views

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1 answer

12

File indexing

asked Jun 7 in Databases by Dipanshu Rana (85 points) | 19 views

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1 answer

13

File indexing

asked Jun 7 in Databases by Dipanshu Rana (85 points) | 24 views

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1 answer

14

Functional dependency

asked Jun 7 in Databases by Dipanshu Rana (85 points) | 40 views

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1 answer

15

Normalization

asked Jun 7 in Databases by Dipanshu Rana (85 points) | 28 views

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1 answer

16

Normalization
A relation with 3 attribute is always in a)4NF b)BCNF c)5)NF d)DK/NF According to me answer must be (b) but answer given in answer sheet is (d) Can any body explain

asked Jun 7 in Databases by Dipanshu Rana (85 points) | 28 views

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17

#Selfdoubt_DBMS
Given R(ABCD) and F : {AB->CD, D->A}. The given relation is in highest normal form possible. Is it FD preserving ?

asked Jun 7 in Databases by Ada (147 points) | 26 views

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18

made easy test series
The total number of schedules that are view equivalent to S are ________.

asked Jun 6 in Databases by Suyash Musalgaonkar (67 points) | 27 views

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1 answer

19

Made easy test series
Consider the following transactions: T1: w(a); w(b); r(c); commit; T2:w(b); r(b); commit; The number schedules of T1 and T2 that are recoverable ________.

asked Jun 6 in Databases by Suyash Musalgaonkar (67 points) | 26 views

+1 vote

2 answers

20

Number of tables
What is minimum number of tables requires, to represent above ER diagram? (Does total participation and partial participation will take a role in this question)?

asked Jun 5 in Databases by srestha Veteran (86.6k points) | 75 views

+1 vote

1 answer

21

SQL Query
Consider relational schema $R(A,B,C)$ and $S(A,B,C)$ $1)$ Select * from $R$ where $(A,B,C)$ in (Select * from $S$) $2)$ Select * from $R$ where exists ( Select * from $S$ where R.A=S.A and R.B=S.B and R.C=S.C) $3)$ Select * from R where $(A,B,C)$ not in((Select * from $R$ where $(A,B,C)$ not in)Select * from S) Which of the following SQL expression equal to $R\cap S$?

asked Jun 5 in Databases by srestha Veteran (86.6k points) | 55 views

+2 votes

1 answer

22

Indexing
Database file consist 50000 records with record size 100 bytes, block size 512 bytes. If sparse B+ tree index build over given database file with search key size 20 bytes both block pointer and record pointer sizes 12 bytes each. How many maximum index blocks required if node order P is defined as between ⎡P/2⎤ to P pointers per node?

asked Jun 4 in Databases by Na462 Active (3.3k points) | 35 views

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2 answers

23

Dirty Read
The Transaction : - T1 T2 R(a) W(a) R(a) C C The above shown schedule is not Dirty read Right ?

asked Jun 2 in Databases by Na462 Active (3.3k points) | 40 views

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0 answers

24

Self Doubt
Which book is better for databases: korth or navathe ?

asked Jun 2 in Databases by Purvi Agrawal Active (2.9k points) | 21 views

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1 answer

25

#Hashing vs Indexing
When we should use hashing and when we should use indexing? what is the difference b/w these two tems ? Explain with taking a practical scenario

asked Jun 1 in Databases by himgta (477 points) | 33 views

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1 answer

26

lost update problem
If schedule is Serializable then free from WW, RW,WR .But Lost update may be possible . please explain how in serializable schedule lost update problem still exist.

asked Jun 1 in Databases by pream sagar (131 points) | 33 views

+1 vote

1 answer

27

WHAT AN INTERESTING DBMS QUESTION!!
Let $E1$ and $E2$ be two entities and $R$ is a relation between $E1$ and $E2$, then what is the minimum no of tables required to represent $E1, E2$ and $R$ if - 1. $E1$ and $E2$ have $1:m$ cardinality($E1$ on $1$ side, $E2$ on $m$ ... ; both $E1$ and $E2$ have total participation. Assume that there is no multi-valued attribute is present in any of the $10$ cases.

asked May 31 in Databases by Balaji Jegan Active (1.1k points) | 98 views

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0 answers

28

Korth Exercise 6.14
member(memb_no, name, dob) books(isbn, title, authors, publisher) borrowed(memb_no, isbn, date) Write the following queries in relational algebra. Find the names of members who have borrowed any books published by "McGraw-Hill" Find the name of ... account that if a member does not borrow any books, then that member does not appear in the borrowed relation at all.

asked May 29 in Databases by Mk Utkarsh Boss (12.6k points) | 98 views

+1 vote

1 answer

29

Normal Forms
Which of the following statement false of relation $R$ is in $3NF$ but not $BCNF$? Relation $R$ must consist atleast two over-lapped candidate keys. Relation $R$ must consist proper subset of candidate key determines proper subset of some other ... other candidate keys simple candidate key. Relation $R$ must consist atleast two compound candidate keys. Please Explain every Option.

asked May 29 in Databases by Na462 Active (3.3k points) | 62 views

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1 answer

30

View Serializability
Consider the following schedules: Which of the following is correct about above schedule? Only view serializable Only conflict serializable Both conflict and view serializable Neither view serializable nor conflict serializable. Please tell me the approach for checking view serializability ?

asked May 29 in Databases by Na462 Active (3.3k points) | 36 views

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