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Introduction
Very simple subqueries
Subqueries with multiple results
Correlated subqueries
15. The IN operator with correlated subqueries
Other subqueries

## Instruction

Great job! Now, remember the IN operator? It allows us to specify a few values in the WHERE clause as opposed to just one value, so it worked a bit like the OR operator coupled with equality. Now, take a look:

SELECT
*
FROM City
WHERE City.CountryId IN (
SELECT
Country.ID
FROM Country
WHERE Country.ID = City.CountryID
AND Country.Population < 40000
);


Can you predict what the above instruction does? It shows all cities from those countries that have a total population of less than 40000.

## Exercise

Show all information about all trips to cities with a city rating lower than 4.

### Stuck? Here's a hint!

Type:

SELECT
*
FROM Trip
WHERE Trip.CityID IN (
SELECT
City.ID
FROM City
WHERE City.ID = Trip.CityID
AND City.Rating < 4
);