SQL

Consider the relational database with the following four schemas and their respective instances.


The number of rows returned by the above SQL query is ___

The relation scheme given below is used to store information about the employees of a company, where empId is the key and deptId indicates the department to which the employee is assigned. Each employee is assigned to exactly one department.

\textsf{emp($\underline{\textsf{empId}}$, name, gender, salary, deptId)}

Consider the following SQL query:

 select deptId, count(*)
from emp
where gender = "female" and salary > (select avg(salary)from emp)
group by deptId;

The above query gives, for each department in the company, the number of female employees whose salary is greater than the average salary of

The SQL query

 SELECT columns
FROM TableA
RIGHT OUTER JOIN TableB
ON A.columnName = B.columnName
WHERE A.columnName IS NULL

returns the following:

Properties of 'DELETE' and 'TRUNCATE' commands indicate that

Consider a relational database containing the following schemas.

The primary key of each table is indicated by underlining the constituent fields.

 SELECT s.sno, s.sname
    FROM Suppliers s, Catalogue c
    WHERE s.sno=c.sno AND
        cost > (SELECT AVG (cost)
                FROM Catalogue
                WHERE pno = 'P4'
                GROUP BY pno) ;

The number of rows returned by the above SQL query is

A relational database contains two tables Student and Performance as shown below:

The primary key of the Student table is Roll_no. For the Performance table, the columns Roll_no. and Subject_code together from the primary key. Consider the SQL query given below:

SELECT S.Student_name, sum(P.Marks)
FROM Student S, Performance P
WHERE  P.Marks  >  84
GROUP BY S.Student_name;

The number of rows returned by the above SQL query is _________ .

Consider the set of relations given below and the SQL query that follows:

 Students: (Roll_number, Name, Date_of_birth )

Coursed: (Course_number, Course_name, Instructor )

Grades: (Roll_number, Course_number, Grade)

SELECT DISTINCT Name

FROM Students, Courses, Grades

WHERE Students.Roll_number = Grades.Roll_number

                            AND   Courses.Intructor =Sriram

                            AND   Courses.Course_number = Grades.Course_number

                            AND   Grades.Grade = A

Which of the following sets is computed by the above query?

Given relations R(w,x) and S(y,z), the result of
SELECT DISTINCT w,x
FROM R,S
is guaranteed to be same as R, if

Consider the following two tables and four queries in SQL.

Which one of the queries above is certain to have an output that is a superset of the outputs of the other three queries?

\begin{array}{|l|l|l|l|l|} \hline \textbf{Employee} & \textbf{Department} & \textbf{OT allowance} \\ \hline \text{RAMA} & \text{Mechanical} & \text{5000} \\\hline \text{GOPI} & \text{Electrical} & \text{2000} \\\hline \text{SINDHU} & \text{Computer} & \text{4000} \\\hline \text{MAHESH} & \text{Civil} & \text{1500} \\\hline \end{array}
What is the output of the following SQL query?

 select count(*) from 
    ((select Employee, Department from Overtime_allowance) 
    natural join 
    (select Department, OT_allowance from Overtime_allowance) 
    as T);