solve problem of database Big Countries

Author: P-ppc

README.md

@@ -34,4 +34,7 @@ All solutions will be accepted!
 |258|[Add Digits](https://leetcode-cn.com/problems/add-digits/description/)|[java/py/js](./algorithms/AddDigits)|Easy|
 |520|[Detect Capital](https://leetcode-cn.com/problems/detect-capital/description/)|[java/py/js](./algorithms/DetectCaptial)|Easy|
 |682|[BaseBall Game](https://leetcode-cn.com/problems/baseball-game/description/)|[java/py/js](./algorithms/BaseBallGame)|Easy|
-|404|[Sum Of Left Leaves](https://leetcode-cn.com/problems/sum-of-left-leaves/description/)|[java/py/js](./algorithms/SumOfLeftLeaves)|Easy|
+|404|[Sum Of Left Leaves](https://leetcode-cn.com/problems/sum-of-left-leaves/description/)|[java/py/js](./algorithms/SumOfLeftLeaves)|Easy|
+
+# Database
+|596|[Big Countries](https://leetcode-cn.com/problems/big-countries/description/)|[mysql](./database/BigCountries)|Easy|

database/BigCountries/README.md

@@ -0,0 +1,2 @@
+# Big Countries
+This problem is easy to solve

database/BigCountries/solution.sql

@@ -0,0 +1 @@
+select name, population, area from World where area > 3000000 or population > 25000000