This SQL query is used to retrieve the names of cities along with their temperature and condition, but with specific conditions:
1. WHERE condition = 'sunny' OR condition = 'cloudy': This part of the query specifies that the "condition" in the "weather" table should be either "sunny" or "cloudy." Using the OR operator, it allows the condition to match either of these values.
2. AND temperature > 70: After specifying the condition, this part of the query checks that the temperature is greater than 70°F. The AND operator is used to ensure that this temperature condition is met in addition to the "sunny" or "cloudy" condition.
By combining these conditions, Option C correctly finds cities where the condition is either "sunny" or "cloudy" and the temperature exceeds 70°F. This results in a list of cities that meet both of these criteria.
32
Find all the tuples having temperature greater than 'Paris'.
To find all the tuples (rows) in the "weather" table where the temperature is greater than the temperature in Paris, you should use the SQL query SELECT * FROM weather WHERE temperature > (SELECT temperature FROM weather WHERE city = 'Paris') (Option A). This query correctly uses a subquery to first select the temperature in Paris and then compares it with the temperatures in other cities. If the temperature in a city is greater than that of Paris, the row is included in the result set. This is why Option A is the correct choice.
33
Find all the cities with temperature, condition and humidity whose humidity is in the range of 63 to 79
To retrieve all the cities along with their temperature, condition, and humidity where the humidity falls within the range of 63 to 79, you should use the SQL query SELECT * FROM weather WHERE humidity BETWEEN 63 AND 79 (Option C). This query correctly uses the BETWEEN operator to specify the humidity range. It will include rows where the humidity value is equal to or greater than 63 and equal to or less than 79, thus giving you cities with humidity within the specified range. This is why Option C is the correct choice.
34
Find the names of the countries whose condition is sunny.
To find the names of countries where the condition is "sunny," you should use the SQL query SELECT country FROM location WHERE city IN (SELECT city FROM weather WHERE condition = 'sunny'); (Option B). This query correctly uses a subquery to first select the cities with a "sunny" condition from the "weather" table and then matches those cities to the "city" column in the "location" table to determine the corresponding countries. Option B is the appropriate choice for obtaining the desired result.
35
Find the name of all cities with their temperature, humidity and countries.
To retrieve the names of all cities along with their temperature, humidity, and countries, you should use the SQL query SELECT weather.city, temperature, humidity, country FROM weather, location WHERE weather.city = location.city; (Option C). This query correctly joins the "weather" and "location" tables based on the "city" column, which is common between the two tables. This allows you to obtain the information for all cities, including their temperature, humidity, and corresponding countries. Option C is the appropriate choice for achieving this result.
36
Find the name of cities with all entries whose temperature is in the range of 71 and 89
To retrieve the names of cities with entries where the temperature falls within the range of 71 to 89, you should use the SQL query SELECT * FROM weather WHERE temperature BETWEEN 71 AND 89; (Option D). This query utilizes the BETWEEN operator to specify the temperature range. It selects all entries in the "weather" table where the temperature is within the specified range. Option D is the correct choice for achieving this result.
37
Which of the following query finds the names of the sailors who have reserved at least one boat?
To find the names of sailors who have reserved at least one boat, you should use the SQL query SELECT DISTINCT s.sname FROM sailors s, reserves r WHERE s.sid = r.sid; (Option A). This query joins the "sailors" and "reserves" tables on the "sid" column and selects the distinct "sname" (sailor names) from the "sailors" table. The use of DISTINCT ensures that you only get unique sailor names. Option A is the correct choice for achieving this result.
38
Which of the following query finds colors of boats reserved by "Dustin"?
To find the colors of boats reserved by "Dustin," you should use the SQL query 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; (Option B). This query joins the "boats," "reserves," and "sailors" tables to find the colors of boats reserved by "Dustin." It ensures that the sailor's name is "Dustin" (s.sname = 'Dustin') and matches the sailor's ID to the reservation's sailor ID (s.sid = r.sid) and the reservation's boat ID to the boat's ID (r.bid = b.bid). The use of DISTINCT ensures you get unique boat colors. Option B is the correct choice for obtaining this information.
39
What does the following query find?
(SELECT DISTINCT r.sid
FROM boats b, reserves r
WHERE b.bid = r.bid
AND b.color = 'red')
MINUS
(SELECT DISTINCT r.sid
FROM boats b, reserves r
WHERE b.bid = r.bid
AND b.color = 'green')
The given SQL query finds the sailor IDs of all sailors who have reserved red boats but not green boats. It does this by first selecting the sailor IDs (r.sid) of reservations where the boat color is 'red' and then subtracting the sailor IDs of reservations where the boat color is 'green'. The MINUS operator is used to find the set difference, and in this context, it retrieves the sailor IDs of sailors who have reserved red boats but not green boats. Option A is the correct choice for describing the query's result.
40
Which of the following query finds the name of the sailors who have reserved at least two boats?
Both Option A and Option C can be used to find the name of sailors who have reserved at least two boats. They achieve this by joining the "sailors" and "reserves" tables twice, specifying that the sailor IDs (s.sid) should be the same in both reservations, and ensuring that the boat IDs (r1.bid and r2.bid) are different. This identifies sailors who have made multiple reservations. Therefore, the correct answer is Option E, which includes both A and C as valid choices for this query.
