[VTU DBMS PGM 2] Airline Database (involving the tables 'FLIGHTS', 'AIRCRAFT', 'CERTIFIED', 'EMPLOYEES')

Question:

The following relations keep track of airline flight information: 

• Flights (no: integer, src: string, dst: string, distance: integer, Departs: time, arrives: time, price: real) 
• Aircraft (aid: integer, aname: string, cruisingrange: integer) 
• Certified (eid: integer, aid: integer)
• Employees (eid: integer, ename: string, salary: integer)  

Note that the Employees relation describes pilots and other kinds of employees as well. Every pilot is certified for some aircraft, and only pilots are certified to fly.   

Write each of the following queries in SQL. 

Queries:

1. Find the names of aircraft such that all pilots certified to operate them have salaries more than Rs.80, 000.

Method 1.

SELECT DISTINCT A.aname 
FROM AIRCRAFT A, CERTIFIED C 
WHERE A.aid=C.aid AND 
C.eid IN ( SELECT eid 
FROM EMPLOYEES 
WHERE salary > 80000); 

Method 2.

SELECT DISTINCT a.aname 
FROM aircraft a 
WHERE a.aid NOT IN 
( SELECT c.aid 
FROM certified c,employees e 
WHERE c.eid=e.eid AND 
e.salary<80000);

2. For each pilot who is certified for more than three aircrafts, find the eid and the maximum cruisingrange of the aircraft for which she or he is certified.

SELECT C.eid, MAX(a.cruisingrange) 
FROM CERTIFIED C, AIRCRAFT A 
WHERE C.aid=A.aid 
GROUP BY C.eid 
HAVING COUNT(*) > 3;

3. Find the names of pilots whose salary is less than the price of the cheapest route from Bengaluru to Frankfurt.

SELECT E.ename 
FROM EMPLOYEES E 
WHERE E.salary < (SELECT min(price)  
FROM FLIGHTS 
WHERE fromPlace=‘bangalore’ AND 
oPlace='frankfurt');

4. For all aircraft with cruising range over 1000 Kms, .find the name of the aircraft and the average salary of all pilots certified for this aircraft.

select aname, avg(salary) as avgsal 
from aircraft a, certified c, employees e 
where a.crusingrange>1000 and 
c.aid=a.aid and 
c.eid=e.eid 
group by aname;

5. Find the names of pilots certified for some Boeing aircraft.

SELECT DISTINCT E.ename 
FROM AIRCRAFT A, CERTIFIED C, EMPLOYEES E 
WHERE A.aid=C.aid AND 
C.eid=E.eid AND 
A.aname LIKE 'boeing%';

6. Find the aids of all aircraft that can be used on routes from Bengaluru to New Delhi

SELECT A.aid 
FROM AIRCRAFT A 
WHERE A.cruisingrange > (SELECT min(distance) FROM FLIGHTS  
WHERE fromPlace='bangalore' AND 
toPlace = 'delhi');

Author : Unknown

He is a simple passionate tech freak who himself is an engineering student at Canara Engineering college. He likes App Development, Web designing, Blogging, Youtubing, Debugging and also is a CodeGeek!

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