595. Big Countries_leetcode595. big countries-优快云博客

本文介绍了一个使用SQL查询来筛选出面积超过3百万平方公里或人口超过2500万的大国的具体实现方法。通过一个示例表格，展示了如何利用SQL语句进行条件筛选，并给出了正确的SQL查询语句。

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      |
+--------------+-------------+--------------+

解题思路：运用SQL算法，提出name, population, area三列，再用where语句找出符合条件的项。
MYSQL
    SELECT name, population, area FROM world WHERE population > 3000000 OR area > 25000000;