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Welcome to GATE CSE Doubts, where you can ask questions and receive answers from other members of the community.

Recent questions tagged databases

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0 answers 31 views
Can anyone suggest me any good resource or videos for self studying gate CSE maths and Database.I need to finish them fast... DATABASE MANAGEMENT SYSTEMS Syllabus ER-model. Relational model: relational algebra **, tuple calculus **, SQL. Integrity constraints ... .in/281290/how-do-i-prepare-engineering-mathematics-for-gate-cs https://drive.google.com/file/d/0Byt7-j-JD0d0bmxlRkZGcjN2cjA/view
asked Jul 24 in Databases asqwer 633 points 31 views
0 votes
1 answer 15 views
Consider the following schedule S: S: R1(X); R2(Z); R1(Z); R3(X); R3(Y); W1(X); W3(Y); R2(Y); W2(Z); W2(Y); Here Ri(D) denotes that transaction i is reading the data item D while Wi(D) denotes that transaction i is writing the ... operation of the transaction can be added in the end of schedule S in an appropriate order such that S is recoverable. The number of such orders possible are ______
asked Jul 13 in Databases eleven11 5 points 15 views
0 votes
1 answer 17 views
T1 T2 T3 R(A) R(A) W(A) W(A) My approach: Initial reads by: T1 and T2 Final write by: T1 No, Write Read So, T1->T3, T2->T3, and T2->T1 and since T1 occurs last therefore, (T3, T2) → T1 Therefore, T1->T3->T1 and T3<-T2->T1
asked Jul 7 in Databases CheSin 7 points 17 views
0 votes
1 answer 18 views
Consider the relation R(ABCDEF) with dependecies F: {A->C, C->D, B->E, E->F} The number of tables present in its 2NF decomposition are _______.
asked Jul 7 in Databases swami_9 5 points 18 views
0 votes
1 answer 187 views
I am making a list of different types of numericals that can possibly come in GATE from different subjects .. This list is not comprehensive, so please ... ?fbclid=IwAR0ezzTYvJdobF2hXtr3xVNZpZOFtw96yHAywR2_j9BOKGe1mBNSgVUcsvw#9xiori58gq22i 7. https://www.mediafire.com/folder/gp6z7khjzyl8d/gate_materials?fbclid=IwAR0ezzTYvJdobF2hXtr3xVNZpZOFtw96yHAywR2_j9BOKGe1mBNSgVUcsvw#mp3qyi2prh3fb
asked Jul 5 in Others asqwer 633 points 187 views
0 votes
1 answer 50 views
3 Tables , person( Aadhar No. , P .Name, P. addres) Feculty( Aadhar , Salary) Student( Adhar , S_fee,year) can be make 2 table like below in total specialization? Feculty( Aadhar , P .Name, P. addres, Salary) Student( Adhar, P .Name, P. addres , S_fee,year) because I got question in 1 test series where they are saying total specializtion concept wrong.Please show , 2 Tble made are coorect?
asked Jun 29 in Databases Jaykumar12 5 points 50 views
0 votes
0 answers 13 views
hi i am confused with these 3 books as i read GO or any web so all they recommend these 3 and say use these 2 specially (navathe and korth). so i want to ask a question is what one specific book i use to study for all syllabus for dbms or particular ... to topic of syllabus what should i read? which particular topic is good in which book please solve my query cause i stuck in between thank you
asked Jun 27 in Databases ykrishnay 103 points 13 views
0 votes
0 answers 6 views
For the following information systems determine the entities of interest, their attributes and the relationships that exist between the entities. Draw the E-R diagram for the system. Peoples Information Systems for a village/ward(that stores information about peoples)
asked Jun 5 in Databases nasima0058 5 points 6 views
0 votes
1 answer 16 views
Consider the following (incomplete) schedule S: T1:R(X), T1:R(Y), T1:W(X), T2:R(Y), T3:W(Y), T1:W(X), T2:R(Y) If all three transactions eventually commit, show the serializability graph.
asked Jun 4 in Databases Lekhraj 9 points 16 views
0 votes
0 answers 9 views
Consider the following (incomplete) schedule S: T1:R(X), T1:R(Y), T1:W(X), T2:R(Y), T3:W(Y), T1:W(X), T2:R(Y) If all three transactions eventually commit, show the serializability graph.
asked Jun 3 in Databases Lekhraj 9 points 9 views
1 vote
1 answer 22 views
It is 2NF or not ? Just explain this portion.
asked Jun 2 in Databases Enolx.21 53 points 22 views
0 votes
0 answers 11 views
Lets suppose, we define a schema with no primary key but there is an attribute(s) with unique and not null constraints. Now default indexing i.e primary indexing is not possible here because of no primary key. Now, at the time of Database design, If i write ... is it necessary to input records in sorted order? or is there any other way possible to apply clustering index over a given database file?
asked May 30 in Databases bhardwaj.aakash_420 5 points 11 views
0 votes
0 answers 8 views
Consider the following relations concerning a driving school. The primary key of each relation is in boldface. STUDENT(S_Name,Class_No,Th_Mark,Dr_Mark) S_Name - student name, Th-Mark - Theory mark, Dr_Mark - driving mark STUDENT_DRIVING_TEACHER(S_Name,Dr_T_Name) Dr_T_Name - driving ... more marks than average theory mark of class 8. f)Find the list of teachers who can drive all the vehicles.
asked May 29 in Databases nasima0058 5 points 8 views
0 votes
0 answers 8 views
Is the JOIN operations(natural , left , right) in relational algebra and SQL same or is there any difference based on the condition? Please provide reference.
asked May 27 in Databases samir757 29 points 8 views
0 votes
0 answers 7 views
How to find the number of relations required for a self-referential relationship with all the cardinalities mapped with total and partial participation? Please provide links to the same.
asked May 27 in Databases samir757 29 points 7 views
0 votes
0 answers 20 views
R(A,B,C,D) is a relation. FD given is:{ AB->C , C->AD } is it in 2NF? is it in 3NF?
asked May 2 in Databases rishabh8797 5 points 20 views
0 votes
1 answer 21 views
When switching the CPU between two processes.. which of the following applies A. The PCB is both, saved and reloaded, only for the interrupted process that is existing the CPU B. The PCB is saved for the process that is scheduled for the CPU C. The PCB is reloaded for the process that is scheduled for the CPU D. No PCB is saved or reloaded E. None of the above
asked May 2 in Operating System Malak 5 points 21 views
0 votes
0 answers 24 views
So recently I have been studying minimization of ER diagrams and have come across a big confusion. So if 2 entities, E1 and E2 are related to each other with one to one cardinality and E1 has Total participation and E2 has Partial participation, How many minimum tables will ... the answer is 1, but some sources also say that answer should be 2. Also for GATE exam which one should be considered ?
asked Apr 25 in Databases Palash0007 5 points 24 views
0 votes
0 answers 28 views
Why in this question use B-->A ,A-->C ?
asked Apr 23 in Databases Enolx.21 53 points 28 views
0 votes
0 answers 8 views
What is right replication policy in database? And how is it different from right biasing?
asked Apr 19 in Databases dragonball 12 points 8 views
0 votes
1 answer 30 views
is it true that “every strict schedule is cascadeless schedule”?
asked Apr 17 in Databases adas7099 9 points 30 views
0 votes
0 answers 38 views
Relation R (A,B,C,D) with FD'S { A->B, B->C, C->D, D->A } then relation R is decomposed into two relations R1 and R2 such that it is satisfying second normal form, third normal form and BCNF and decomposition is lossy. Then how the attributes are distributed in these two decomposed relations R1 and R2? Note: U is the set of all attributes. 1. 2. 3. 4.
asked Mar 14 in Databases samir757 29 points 38 views
0 votes
0 answers 19 views
Given 3 T1, T2 and T3 transactions which have (2,2), (3,2), (4,2) read and write operations respectively the no of schedules possible using these three transactions are A. 1260 B. 630630 C. 6 D. 63000
asked Mar 9 in Databases samir757 29 points 19 views
0 votes
0 answers 93 views
Given the following relations and SQL query: Student (sid, name, age, address, date of birth, level) Book(bid, title, author) Checkout(sid, bid, date_borrowed, date_returned) SELECT S.sid, S.level, C.date_borrowed, C.date_returned FROM Student S, Book B, Checkout C ... correctness of the query using a Relation Connection Graph.[5 marks] d) Represent the query above using a query tree. [5 marks]
asked Mar 6 in Databases Drackelyone 5 points 93 views
1 vote
2 answers 72 views
Suppose we have two entity sets person, Email and use a relationship Owns. A person own atmost one email account but an email account can be owned by multiple persons. Which of the following is an ER diagram based on above description.
asked Mar 2 in Databases IrfanRza 9 points 72 views
1 vote
1 answer 34 views
What is degree of Self Referential Relationship? Unary or Binary?
asked Feb 24 in Databases adas7099 9 points 34 views
3 votes
3 answers 62 views
Q. R(A,B,C,D,E,F) with {A,BC,CD} candidate keys.How many super keys possible?
asked Feb 23 in Databases Enolx.21 53 points 62 views
0 votes
0 answers 18 views
Can Somebody know how to design ER Diagram from this ?
asked Feb 21 in Databases ghostman23111 5 points 18 views
4 votes
4 answers 956 views
Consider the following statements $S1$ and $S2$ about the relational data model: $S1$: A relation scheme can have at most one foreign key. $S2$: A foreign key in a relation scheme $R$ cannot be used to refer to tuples of $R.$ Which one of the following choices is correct? Both $S1$ and $S2$ are true $S1$ is true and $S2$ is false $S1$ is false and $S2$ is true Both $S1$ and $S2$ are false
asked Feb 18 in Databases Arjun 1.5k points 956 views
1 vote
2 answers 556 views
The relation scheme given below is used to store information about the employees of a company, where $\textsf{empId}$ is the key and $\textsf{deptId}$ indicates the department to which the employee is assigned. Each employee is assigned to exactly ... than the average salary of employees in the department employees in the company female employees in the department female employees in the company
asked Feb 18 in Databases Arjun 1.5k points 556 views
0 votes
2 answers 706 views
Let $S$ be the following schedule of operations of three transactions $T_1$, $T_2$ and $T_3$ in a relational database system: $R_2(Y), R_1(X), R_3(Z), R_1(Y)W_1(X), R_2(Z), W_2(Y), R_3(X), W_3(Z)$ Consider the statements $P$ and $Q$ below: $P$: $S$ is conflict- ... correct? Both $P$ and $Q$ are true $P$ is true and $Q$ is false $P$ is false and $Q$ is true Both $P$ and $Q$ are false
asked Feb 18 in Databases Arjun 1.5k points 706 views
0 votes
1 answer 611 views
Suppose the following functional dependencies hold on a relation $U$ with attributes $P,Q,R,S$, and $T$: $P \rightarrow QR$ $RS \rightarrow T$ Which of the following functional dependencies can be inferred from the above functional dependencies? $PS \rightarrow T$ $R \rightarrow T$ $P \rightarrow R$ $PS \rightarrow Q$
asked Feb 18 in Databases Arjun 1.5k points 611 views
5 votes
2 answers 1K views
Suppose a database system crashes again while recovering from a previous crash. Assume checkpointing is not done by the database either during the transactions or during recovery. Which of the following statements is/are correct? The same undo and redo list ... any further All the transactions that are already undone and redone will not be recovered again The database will become inconsistent
asked Feb 18 in Databases Arjun 1.5k points 1K views
3 votes
1 answer 1.7K views
A relation $r(A, B)$ in a relational database has $1200$ tuples. The attribute $A$ has integer values ranging from $6$ to $20$, and the attribute $B$ has integer values ranging from $1$ to $20$. Assume that the attributes $A$ and $B$ are independently distributed. The estimated number of tuples in the output of $\sigma _{(A>10)\vee(B=18)}(r)$ is ____________.
asked Feb 18 in Databases Arjun 1.5k points 1.7K views
0 votes
1 answer 513 views
The following relation records the age of $500$ employees of a company, where $empNo$ (indicating the employee number) is the key: $empAge(\underline{empNo},age)$ ... one other employee Employee numbers of all employees whose age is not the minimum Employee numbers of all employees whose age is the minimum
asked Feb 18 in Databases Arjun 1.5k points 513 views
3 votes
3 answers 480 views
Let $r_i(z)$ and $w_i(z)$ denote read and write operations respectively on a data item $z$ by a transaction $T_i$. Consider the following two schedules. $S_1: r_1(x)r_1(y)r_2(x)r_2(y)w_2(y)w_1(x)$ ... $S_2$ is conflict serializable Both $S_1$ and $S_2$ are conflict serializable Niether $S_1$ nor $S_2$ is conflict serializable
asked Feb 18 in Databases Arjun 1.5k points 480 views
1 vote
5 answers 928 views
Consider the relation $R(P,Q,S,T,X,Y,Z,W)$ with the following functional dependencies. $PQ\rightarrow X;\quad P\rightarrow YX;\quad Q\rightarrow Y; \quad Y\rightarrow ZW$ Consider the decomposition of the relation $R$ into the constituent relations according to ... , but $D_2$ is a lossless decomposition Both $D_1$ and $D_2$ are lossless decompositions Both $D_1$ and $D_2$ are lossy decompositions
asked Feb 18 in Databases Arjun 1.5k points 928 views
1 vote
0 answers 29 views
Consider a database implemented using B+ tree for file indexing and installed on a disk drive with block size of 4 KB. The size of search key is 12 bytes and the size of tree/disk pointer is 8 bytes. Assume that the database has one million records. Also ... that each record fits into one disk block. The minimum number of disk accesses required to retrieve any record in the database is ______.
asked Feb 13 in Databases Enolx.21 53 points 29 views
0 votes
0 answers 29 views
In this question, it is asked to retrieve the name of each employee who has a dependent with the same first name and is the same sex as employee. How Q1 will give the correct result, coz inside IN() the condition Essn=D,Essn is not there. Can anybody explain.
asked Feb 6 in Databases Ankita87077 11 points 29 views
0 votes
0 answers 44 views
Consider the following table: A B C a1 b1 c1 a1 b1 c2 a2 b1 c1 a2 b1 c3 Number of non-trivial functional dependencies exists in the above Table ___________.
asked Feb 4 in Databases vikashrajpoot0100 5 points 44 views
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