Consider the relations described below:
PHYSICIAN (regno, name, telno, city)
PATIENT (pname, street, city)
VISIT (pname, regno, date_of_visit, fee)
Where the regno and pname identify the physician and the patient uniquely corresponding. Express queries (i) to (iii) in SQL.
(i) Get the name and regno of physicians who are in Delhi.
(ii) Find out the name and city of patient(s) who visited a physician on 31 August 2004.
(iii) Get the name of the physician and the total number of patients who have visited her.
(iv) What does the subsequent SQL query answer
SELECT DISTINCT name
FROM PHYSICIAN P
WHERE NOT EXISTS
( SELECT *
FROM VISIT
WHERE regno = p.regno )

(i) Select name, regno from PHYSICIAN where city = ‘Delhi';
(ii) Select pname, city from PATIENT,VISIT where PATIENT.pname=VISIT.pname and date_of_visit = '31-Aug-04';
(iii) select name, count(*) from PHYSICIAN, VISIT where PHYSICIAN.regno = VISIT.regno group by Physician . regno;
(iv) This will provide the name of physicians who have not visited any patient.