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sql notes: leetcode#595 big countries

admin 11月 12, 2020 0

Problem

There is a table World

+-----------------+------------+------------+--------------+---------------+
| name            | continent  | area       | population   | gdp           |
+-----------------+------------+------------+--------------+---------------+
| Afghanistan     | Asia       | 652230     | 25500100     | 20343000      |
| Albania         | Europe     | 28748      | 2831741      | 12960000      |
| Algeria         | Africa     | 2381741    | 37100000     | 188681000     |
| Andorra         | Europe     | 468        | 78115        | 3712000       |
| Angola          | Africa     | 1246700    | 20609294     | 100990000     |
+-----------------+------------+------------+--------------+---------------+

A country is big if it has an area of bigger than 3 million square km or a population of more than 25 million.

Write a SQL solution to output big countries’ name, population and area.

For example, according to the above table, we should output:

+--------------+-------------+--------------+
| name         | population  | area         |
+--------------+-------------+--------------+
| Afghanistan  | 25500100    | 652230       |
| Algeria      | 37100000    | 2381741      |
+--------------+-------------+--------------+

Anlysis

Output name, population and area ==> SELECT name, population, area
Table World ==> FROM World
area bigger than 3 million square km ==> area > 3000000
population more than 25 million ==> population > 25000000
big country if area bigger than 3 million square km or population more than 25 million ==> WHERE area > 3000000 OR population > 25000000

Solution

1	SELECT name, population, area FROM World WHERE area > 3000000 OR population > 25000000;

Link

595. Big Countries
(中文版) SQL 笔记: Leetcode#595 Big Countries