Add solution 595 [sql]

Author: yanglbme

README.md

@@ -42,6 +42,7 @@ Complete [solutions](https://github.com/doocs/leetcode/tree/master/solution) to
 | 237 | [Delete Node in a Linked List](https://github.com/doocs/leetcode/tree/master/solution/237.Delete%20Node%20in%20a%20Linked%20List) | `Linked List` |
 | 344 | [Reverse String](https://github.com/doocs/leetcode/tree/master/solution/344.Reverse%20String) | `Two Pointers`, `String` |
 | 581 | [Shortest Unsorted Continuous Subarray](https://github.com/doocs/leetcode/tree/master/solution/581.Shortest%20Unsorted%20Continuous%20Subarray) | `Array` |
+| 595 | [Big Countries](https://github.com/doocs/leetcode/tree/master/solution/595.Big%20Countries) | `SQL` |
 | 605 | [Can Place Flowers](https://github.com/doocs/leetcode/tree/master/solution/605.Can%20Place%20Flowers) | `Array` |
 | 695 | [Max Area of Island](https://github.com/doocs/leetcode/tree/master/solution/695.Max%20Area%20of%20Island) | `Array`, `Depth-first Search` |
 | 703 | [Kth Largest Element in a Stream](https://github.com/doocs/leetcode/tree/master/solution/703.Kth%20Largest%20Element%20in%20a%20Stream) | `Heap` |
@@ -100,6 +101,7 @@ Complete [solutions](https://github.com/doocs/leetcode/tree/master/solution) to
 ## Contributions
 I'm looking for long-term contributors/partners to this repo! Send me [PRs](https://github.com/doocs/leetcode/pulls) if you're interested! See the following:
 - Fork this repository to your own GitHub account and then [clone](https://help.github.com/articles/cloning-a-repository/) it to your local device.
+- Add or update file of the repository, then commit and push it to your GitHub repository.
 - Submit a pull request with your changes!
 
 ![how-to-contribute](http://p9ucdlghd.bkt.clouddn.com/how-to-contribute-yanglbme.png)

solution/595.Big Countries/README.md

@@ -0,0 +1,37 @@
+## 大的国家
+### 题目描述
+
+这里有张 `World` 表
+```
++-----------------+------------+------------+--------------+---------------+
+| 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     |
++-----------------+------------+------------+--------------+---------------+
+```
+
+如果一个国家的面积超过300万平方公里，或者人口超过2500万，那么这个国家就是大国家。
+
+编写一个SQL查询，输出表中所有大国家的名称、人口和面积。
+
+例如，根据上表，我们应该输出:
+```
++--------------+-------------+--------------+
+| name         | population  | area         |
++--------------+-------------+--------------+
+| Afghanistan  | 25500100    | 652230       |
+| Algeria      | 37100000    | 2381741      |
++--------------+-------------+--------------+
+```
+
+### 解法
+
+```sql
+# Write your MySQL query statement below
+select distinct name, population, area from World where area > 3000000 or population > 25000000
+
+```