# Recent questions tagged databases

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
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 ______
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
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 _______.
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
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?
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
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)
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.
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.
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It is 2NF or not ? Just explain this portion.
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?
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.
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.
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.
R(A,B,C,D) is a relation. FD given is:{ AB->C , C->AD } is it in 2NF? is it in 3NF?
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
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 ?
Why in this question use B-->A ,A-->C ?
What is right replication policy in database? And how is it different from right biasing?
is it true that “every strict schedule is cascadeless schedule”?
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.
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
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]
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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.
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What is degree of Self Referential Relationship? Unary or Binary?
Q. R(A,B,C,D,E,F) with {A,BC,CD} candidate keys.How many super keys possible?
Can Somebody know how to design ER Diagram from this ?
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
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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
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
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? $PS \rightarrow T$ $R \rightarrow T$ $P \rightarrow R$ $PS \rightarrow Q$
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
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 ____________.
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
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
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