Recent questions tagged databases

The following table refers to search items for a key in $B$-trees and $B^+$ trees.$$\begin{array}{|ll|ll|} \hline & \textbf {B-tree} & & \textbf {B}^+\text{-tree} \\\hl...

For relation R = (L, M, N, O, P), the following dependencies hold:$ M \rightarrow O,$ $NO \rightarrow P,$ $P \rightarrow L$ and $L \rightarrow MN$R is decomposed into R1 ...

From the following instance of a relation schema $R(A,B,C)$, we can conclude that:$$\begin{array}{|l|l|}\hline \textbf{A} & \textbf{B} & \textbf{C} \\\hline \text{1} & \...

Relation $R$ is decomposed using a set of functional dependencies, $F$, and relation $S$ is decomposed using another set of functional dependencies, $G$. One decompositio...

A $B^+$ - tree index is to be built on the Name attribute of the relation STUDENT. Assume that all the student names are of length $8$ bytes, disk blocks are of size $512...

With regards to the expressive power of the formal relational query languages, which of the following statements is true?Relational algebra is more powerful than relation...

Relation $R$ with an associated set of functional dependencies, $F$, is decomposed into $\text{BCNF}$. The redundancy (arising out of functional dependencies) in the resu...

We wish to construct a $B^+$ tree with fan-out (the number of pointers per node) equal to $3$ for the following set of key values:$80, 50, 10, 70, 30, 100, 90$Assume that...

Consider a relation examinee (regno, name, score), where regno is the primary key to score is a real number.Write a relational algebra using $( \Pi, \sigma, \rho, \times)...

Consider a relation geq which represents "greater than or equal to", that is, $(x,y) \in $ geq only if $y \geq x$.create table geq ( ib integer not null, ub integer not n...

Which of the following relational calculus expression is not safe?$\left\{t \mid \exists u \in R_1\left(t[A] = u[A]\right) \land \neg \exists s \in R_2 \left(t[A] = s[A]\...

$R(A,B,C,D)$ is a relation. Which of the following does not have a lossless join, dependency preserving $BCNF$ decomposition?$A \rightarrow B, B \rightarrow CD$$A \righta...

Let r and s be two relations over the relation schemes R and S respectively, and let A be an attribute in R. The relational algebra expression $\sigma_{A=a}(r \bowtie s)...

Suppose the adjacency relation of vertices in a graph is represented in a table Adj $(X,Y).$ Which of the following queries cannot be expressed by a relational algebra ex...

Consider a schema $R(A,B,C,D)$ and functional dependencies $A \rightarrow B$ and $C \rightarrow D$. Then the decomposition of R into $R_1 (A,B)$ and $R_2(C,D)$ isdependen...

In SQL, relations can contain null values, and comparisons with null values are treated as unknown. Suppose all comparisons with a null value are treated as false. Which ...

Given relations r(w, x) and s(y, z) the result ofselect distinct w, x from r, s is guaranteed to be same as r, provided.r has no duplicates and s is non-emptyr and s have...

Given the following relation instance.$$\begin{array}{|l|l|}\hline \text{X} & \text{Y} & \text{Z} \\\hline \text{1} & \text{4} & \text{2} \\ \text{1} & \text{5} & \te...

Given the relationsemployee (name, salary, dept-no), anddepartment (dept-no, dept-name,address),Which of the following queries cannot be expressed using the basic relatio...

B$^{+}$-trees are preferred to binary trees in databases becauseDisk capacities are greater than memory capacitiesDisk access is much slower than memory accessDisk data t...

Suppose a database consist of the following relations:SUPPLIER (SCODE,SNAME,CITY). PART (PCODE,PNAME,PDESC,CITY). PROJECTS (PRCODE,PRNAME,PRCITY). SPPR (SCODE,PCODE,PRCOD...

Consider the following relational schemes for a library database:Book (Title, Author, Catalog_no, Publisher, Year, Price) Collection(Title, Author, Catalog_no)with the fo...

Let R and S be two relations with the following schema$R(\underline{P,Q}, R1, R2, R3)$$S(\underline{P,Q}, S1, S2)$where $\left\{P, Q\right\}$ is the key for both schemas....

A B-tree of order $4$ is built from scratch by $10$ successive insertions. What is the maximum number of node splitting operations that may take place?$3$$4$$5$$6$

A clustering index is defined on the fields which are of typenon-key and orderingnon-key and non-orderingkey and orderingkey and non-ordering

Which of the following tuple relational calculus expression(s) is/are equivalent to $\forall t \in r \left(P\left(t\right)\right)$?$\neg \exists t \in r \left(P\left(t\ri...