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Exercise

Advanced subquery

You can also nest multiple subqueries to answer even more specific questions.

In this exercise, for each of the six continents listed in 2015, you'll identify which country had the maximum inflation rate, and how high it was, using multiple subqueries. The table result of your final query should look something like the following, where anything between < > will be filled in with appropriate values:

+------------+---------------+-------------------+
| name       | continent     | inflation_rate    |
|------------+---------------+-------------------|
| <country1> | North America | <max_inflation1>  |
| <country2> | Africa        | <max_inflation2>  |
| <country3> | Oceania       | <max_inflation3>  |
| <country4> | Europe        | <max_inflation4>  |
| <country5> | South America | <max_inflation5>  |
| <country6> | Asia          | <max_inflation6>  |
+------------+---------------+-------------------+

Again, there are multiple ways to get to this solution using only joins, but the focus here is on showing you an introduction into advanced subqueries.

Instructions 1/3

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  • Create an INNER JOIN with countries on the left and economies on the right with USING, without aliasing your tables or columns.
  • Retrieve the country's name, continent, and inflation rate for 2015.