sql mcq Questions and answers

1 . Which of the following query finds the total rating of the sailors who have reserved boat "103"?

• SELECT SUM(s.rating) FROM sailors s, reserves r WHERE s.sid = r.sid AND r.bid = 103
• SELECT COUNT(s.rating) FROM sailors s, reserves r WHERE s.sid = r.sid AND r.bid = 103
• SELECT s.rating FROM sailors s, reserves r WHERE s.sid = r.sid AND r.bid = 103
• SELECT SUM(s.rating) FROM sailors s, reserves r AND r.bid = 103

2 . The SELECT statement SELECT 'Hi' FROM DUAL WHERE NULL = NULL; Outputs

• NO
• TRUE
• FALSE
• NONE

3. Which of the following is illegal?

• SELECT SYSDATE - SYSDATE FROM DUAL
• SELECT SYSDATE - (SYSDATE - 2) FROM DUAL
• SELECT SYSDATE - (SYSDATE + 2) FROM DUAL
• None

4 . If a query involves NOT, AND, OR with no parenthesis:

• NOT will be evaluated first; AND will be evaluated second; OR will be evaluated last
• NOT will be evaluated first; OR will be evaluated second; AND will be evaluated last
• The order of occurrence determines the order of evaluation
• AND will be evaluated first; OR will be evaluated second; NOT will be evaluated last

5. Find the name of cities with all entries whose temperature is in the range of 71 and 89:

• FROM weather WHERE temperature NOT IN (71 to 89)
• FROM weather WHERE temperature NOT IN (71 and 89)
• FROM weather WHERE temperature NOT BETWEEN 71 to 89
• FROM weather WHERE temperature BETWEEN 71 AND 89

6 . Which of the following query finds the names of the sailors who have reserved at least one boat?

• SELECT DISTINCT s.sname FROM sailors s, reserves r WHERE s.sid = r.sid
• SELECT s.sname FROM sailors s, reserves r WHERE s.sid = r.sid
• SELECT DISTINCT s.sname FROM sailors, reserves WHERE s.sid = r.sid
• None

7 . Which of the following query finds colors of boats reserved by "Dustin"?

• SELECT DISTINCT b.color FROM boats b, sailors s WHERE s.sname = 'Dustin' AND s.sid = b.sid
• SELECT DISTINCT b.color FROM boats b, reserves r, sailors s WHERE s.sname = 'Dustin' AND s.sid = r.sid AND r.bid = b.bid
• SELECT DISTINCT b.color FROM boats b, reserves r, sailors s WHERE s.sname = 'Dustin' AND s.sid = r.sid
• SELECT DISTINCT b.color FROM boats b, reserves r, sailors s WHERE s.sname = 'Dustin' AND r.bid = b.bid

8 . Which of the following query finds the name of the sailors who have reserved at least two boats?

• SELECT DISTINCT s.sname FROM sailors s, reserves r1, reserves r2 WHERE s.sid = r1.sid AND r1.sid = r2.sid AND r1.bid ≠ r2.bid
• SELECT DISTINCT s.sname FROM sailors s, reserves r1, reserves r2 WHERE s.sid = r1.sid AND COUNT(r1.bid) > r2.bid
• SELECT DISTINCT s.sname FROM sailors s, reserves r1, reserves r2 WHERE s.sid = r1.sid AND r1.sid = r2.sid AND r1.bid <> r2.bid
• All of these

9 . Which command undo all the updates performed by the SQL in the transaction?

• ROLLBACK
• COMMIT
• TRUNCATE
• DELETE

10. Find all the cities whose humidity is 89:

• SELECT city WHERE humidity = 89
• SELECT city FROM weather WHERE humidity = 89
• SELECT humidity = 89 FROM weather
• SELECT city FROM weather