Introduction
Very simple subqueries
Subqueries with multiple results
Correlated subqueries
Instruction
Okay! Now, you're probably wondering how to use the new IN operator with subqueries. Consider the following example:
SELECT
Trip.Price
FROM Trip
WHERE Trip.CityID IN (
SELECT
City.ID
FROM City
WHERE City.Population < 2000000
);
In this subquery, we look for the IDs of all cities with a population of less than 2 million. Next, we use these IDs as the values in the IN operator.
In this way, we can find the prices of trips to cities with fewer lower than 2 million people.
Exercise
Find all information about all trips in cities with an area exceeding 100.
Stuck? Here's a hint!
Type:
SELECT
*
FROM Trip
WHERE Trip.CityID IN (
SELECT
City.ID
FROM City
WHERE City.Area > 100
);
