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Higher Study | DBMS | Query Language

What is the full form of SQL?
Which of the following is not a logical data-base structure?
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. emp(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
Consider the relational schema given below, where eId of the relation dependent is a foreign key referring to empId of the relation employee. Assume that every employee has at least one associated dependent in the dependent relation. Employee (empId, empName, empAge) Dependent(depId, eId, depName, depAge) Consider the following relational algebra query: ΠempId(employee)-ΠempId (employee⋈(empId = eID)∧(empAge ≤ depAge)dependent) The above query evaluates to the set of empIds of employees whose age is greater than that of
Which of the following Relational Algebra operations can be used when you want to keep all the tuples of the first relation irrespective of whether or not they have matching tuples in the second relation?
Consider the following relation schema: Product(id, name, price) What will be the output of the following SQL code? SELECT max(price) FROM Product WHERE price < (SELECT max(price) FROM Product);
Let R and S be two database relations. If cardinalities of R and S are 4 and 10, respectively, then what will be the number of tuples in R × S, where '×' represents cross product operation?
Consider the relation schemas R(A, B, C, D) and S(D, E, F). What will be the degree of the resultant schema R * S, where star (*) symbol represents the natural join operation?
A relational schema for a train reservation database is given below Passenger (pid, pname, age) Re servation (pid, cass, tid) Table : Passenger pid ‘pname Age 0 ‘Sachin’ 65 1 ‘Rahul’ 66 2 ‘Sourav’ 67 3 ‘Anil’ 69   Table : Reservation pid class tid 0 ‘AC’ 8200 1 ‘AC’ 8201 2 ‘SC’ 8201 5 ‘AC’ 8203 1 'SC' 8204 3 'AC' 8202 What pids are returned by the following SQL query for the above instance of the tables? SELECT pid FROM Reservation WHERE class 'AC ' AND                EXISTS (SELECT *                            FROM Passenger                             WHERE age > 65 AND                              Passenger.pid = Reservation.pid)
Suppliers(Sid: integer, sname:string, city:string, street:string) Parts(pid:integer, pname:string, color:string) Catalog(sid:integer, pid:integer, cost:real) Consider the following relational query on the above database: SELECT S.sname FROM Suppliers S  WHERE S.sid NOT IN (SELECT C.sid FROM Catalog C WHERE C.pid NOT IN (SELECT P.pid FROM Parts P WHERE P.color < > ‘blue’)) Assume that relations corresponding to the above schema are not empty. Which of the following is the correct interpretation of the above query?
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? [select title from book as B where (select count(*) from book as T where T.price > B.price) < 5]
Let P be a procedure that for some inputs calls itself ( i.e. is recursive ). If P is guaranteed to terminate, which of the following statement(s) must be true? I. P has a local variable ll. P has an execution path where it does not call itself II. P either refers to a global variable or has at least one parameter
What is the optimized version of the relation algebra expression πA1(πA2( σF1(σ F2(r)))), where F1, F2 are sets of attributes in r with F1 ⊂ F2 and F1, F2 are Boolean expressions based on the attributes in r?
Consider the following relational schema: employee(empId,empName,empDept) customer(custId,custName,salesRepId,rating) salesRepId is a foreign key referring to empId of the employee relation. Assume that each employee makes a sale to at least one customer. What does the following query return? SELECT empName FROM employee E WHERE NOT EXISTS (SELECT custId FROM customer C WHERE C.salesRepId = E.empId AND C.rating <> ’GOOD’);
Given the following statements: S1: A foreign key declaration can always be replaced by an equivalent check assertion in SQL. S2: Given the table R (a, b, c) where a and b together form the primary key, the following is a valid table definition. CREATE TABLE S (                 a INTEGER,                 d INTEGER,                 e INTEGER,                 PRIMARY KEY (d)                 FOREIGN KEY (a) references R) Which one of the following statements is CORRECT?
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