Recent questions tagged databases

Consider the join of a relation $R$ with a relation $S$. If $R$ has $m$ tuples and $S$ has $n$ tuples then the maximum and minimum sizes of the join respectively are$m+n$...

An index is clustered, ifit is on a set of fields that form a candidate keyit is on a set of fields that include the primary keythe data records of the file are organized...

Consider a relation scheme $R = (A, B, C, D, E, H)$ on which the following functional dependencies hold: {$A \rightarrow B$, $BC \rightarrow D$, $E \rightarrow C$, $D \ri...

The relation book (title, price) contains the titles and prices of different books. Assuming that no two books have the same price, what does the following SQL query list...

The following table has two attributes $A$ and $C$ where $A$ is the primary key and $C$ is the foreign key referencing $A$ with on-delete cascade.$$\begin{array}{|c|c|} \...

Let $E_1$ and $E_2$ be two entities in an $E/R$ diagram with simple-valued attributes. $R_1$ and $R_2$ are two relationships between $E_1$ and $E_2$, where $R_1$ is one-t...

Let r be a relation instance with schema R = (A, B, C, D). We define $r_1 = \pi_{A, B, C} (R)$ and $r_2=\pi_{A, D} (r)$. Let $s =r_1 \: * \: r_2$ where $*$ denotes natura...

Which one of the following statements about normal forms is $\text{FALSE}?$$\text{BCNF}$ is stricter than $\text{3NF}$Lossless, dependency-preserving decomposition into $...

Which of the following is a key factor for preferring $B^+$-trees to binary search trees for indexing database relations?Database relations have a large number of records...

Consider the following relational schema:$\text{Suppliers}(\underline{\text{sid:integer}},\text{ sname:string, city:string, street:string})$ $\text{Parts}(\underline{\tex...

Let $R$ and $S$ be relational schemes such that $R=\{a,b,c\}$ and $S=\{c\}.$ Now consider the following queries on the database:$\pi_{R-S}(r) - \pi_{R-S} \left (\pi_{R-S}...

The following key values are inserted into a $B^+$ - tree in which order of the internal nodes is $3$, and that of the leaf nodes is $2$, in the sequence given below. The...

Consider two transactions $T_1$ and $T_2$, and four schedules $S_1, S_2, S_3, S_4$, of $T_1$ and $T_2$ as given below:$T_1: R_1[x]W_1[x]W_1[y]$$T_2: R_2[x]R_2[y]W_2[y...

Consider table R(A,B,C,D,E) with FDs as A->B, BC->E and ED- A. The table is in which normal form? Justify your answer.

Consider the following schedules involving two transactions. Which one of the following statements is TRUE?$S_1 :r_1(X); r_1(Y); r_2(X); r_2(Y); w_2(Y); w_1(X)$$S_2 :r_1(...

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

Which one of the following statements is $\text{FALSE}$?Any relation with two attributes is in $\text{BCNF}$A relation in which every key has only one attribute is in $\t...

Consider the table employee(empId, name, department, salary) and the two queries $Q_1, \, Q_2$ below. Assuming that department $5$ has more than one employee, and we want...

Consider the relation employee(name, sex, supervisorName) with name as the key, supervisorName gives the name of the supervisor of the employee under consideration. What ...

The employee information in a company is stored in the relationEmployee (name, sex, salary, deptName)Consider the following SQL querySelect deptName From Employee Where s...

The order of an internal node in a $B+$ tree index is the maximum number of children it can have. Suppose that a child pointer takes $6$ bytes, the search field value tak...

Consider the relation Student (name, sex, marks), where the primary key is shown underlined, pertaining to students in a class that has at least one boy and one girl. Wha...

The relation scheme $\text{Student Performance (name, courseNo, rollNo, grade)}$ has the following functional dependencies:name, courseNo, $\rightarrow$ graderollNo, cour...

Consider the following relation schema pertaining to a students database:Students (rollno, name, address)Enroll (rollno, courseno, coursename)where the primary keys are s...

Let $R_1 \left(\underline{A}, B, C\right)$ and $R_2\left(\underline{D}, E \right) $ be two relation schema, where the primary keys are shown underlined, and let C be a fo...

Consider the following log sequence of two transactions on a bank account, with initial balance $12000,$ that transfer $2000$ to a mortgage payment and then apply a $5\%$...

Consider three data items $D1, D2,$ and $D3,$ and the following execution schedule of transactions $T1, T2,$ and $T3.$ In the diagram, $R(D)$ and $W(D)$ denote the action...

Consider the set of relations shown below and the SQL query that follows.Students: (Roll_number, Name, Date_of_birth)Courses: (Course_number, Course_name, Instructor)Grad...

Consider the following functional dependencies in a database.$$\begin{array}{|l|l|}\hline \text{Date_of_Birth } \to \text{Age} & \text{Age } \to \text{Eligibility} \\\hli...

Consider the following $2-3-4$ tree (i.e., B-tree with a minimum degree of two) in which each data item is a letter. The usual alphabetical ordering of letters is used in...