From 821a18ea38655fc8f513e724ddc8ecca816a9eb2 Mon Sep 17 00:00:00 2001
From: Gabriel <gabriell.vasile@gmail.com>
Date: Thu, 2 May 2019 17:28:58 +0800
Subject: [PATCH] Solution for 10th question in SELECT within SELECT

---
 4_soutions.sql | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/4_soutions.sql b/4_soutions.sql
index 2d1cec0..8d31485 100644
--- a/4_soutions.sql
+++ b/4_soutions.sql
@@ -47,3 +47,13 @@ GROUP BY continent
 HAVING max(population) <= 25000000) AS x
 ON y.continent = x.continent
 
+--10. Some countries have populations more than three times that of any of their neighbours (in the same continent). Give the countries and continents.
+SELECT name, continent
+FROM world w1
+WHERE population >= 
+  ALL(
+    SELECT population * 3 FROM world w2
+    WHERE w1.continent = w2.continent
+    AND w1.name <> w2.name
+  )
+