Add solution 197 [sql]

inner join
datediff()

Author: yanglbme

README.md

@@ -41,6 +41,7 @@ Complete [solutions](https://github.com/doocs/leetcode/tree/master/solution) to
 | 183 | [Customers Who Never Order](https://github.com/doocs/leetcode/tree/master/solution/183.Customers%20Who%20Never%20Order) | `SQL` |
 | 189 | [Rotate Array](https://github.com/doocs/leetcode/tree/master/solution/189.Rotate%20Array) | `Array` |
 | 196 | [Delete Duplicate Emails](https://github.com/doocs/leetcode/tree/master/solution/196.Delete%20Duplicate%20Emails) | `SQL` |
+| 197 | [Rising Temperature](https://github.com/doocs/leetcode/tree/master/solution/197.Rising%@0Temperature) | `SQL` |
 | 198 | [House Robber](https://github.com/doocs/leetcode/tree/master/solution/198.House%20Robber) | `Dynamic Programming` |
 | 203 | [Remove Linked List Elements](https://github.com/doocs/leetcode/tree/master/solution/203.Remove%20Linked%20List%20Elements) | `Linked List` |
 | 231 | [Power of Two](https://github.com/doocs/leetcode/tree/master/solution/231.Power%20of%20Two) | `Math`, `Bit Manipulation` |

solution/197.Rising Temperature/README.md

@@ -0,0 +1,46 @@
+## 上升的温度
+### 题目描述
+
+
+给定一个 `Weather` 表，编写一个 SQL 查询，来查找与之前（昨天的）日期相比温度更高的所有日期的 Id。
+```
++---------+------------------+------------------+
+| Id(INT) | RecordDate(DATE) | Temperature(INT) |
++---------+------------------+------------------+
+|       1 |       2015-01-01 |               10 |
+|       2 |       2015-01-02 |               25 |
+|       3 |       2015-01-03 |               20 |
+|       4 |       2015-01-04 |               30 |
++---------+------------------+------------------+
+```
+
+例如，根据上述给定的 `Weather` 表格，返回如下 Id:
+```
++----+
+| Id |
++----+
+|  2 |
+|  4 |
++----+
+```
+
+### 解法
+利用 datediff 函数返回两个日期相差的天数。
+
+```sql
+# Write your MySQL query statement below
+select a.Id
+from Weather a
+inner join Weather b
+on a.Temperature > b.Temperature and datediff(a.RecordDate, b.RecordDate) = 1;
+```
+
+#### Input
+```json
+{"headers": {"Weather": ["Id", "RecordDate", "Temperature"]}, "rows": {"Weather": [[1, "2015-01-01", 10], [2, "2015-01-02", 25], [3, "2015-01-03", 20], [4, "2015-01-04", 30]]}}
+```
+
+#### Output
+```json
+{"headers":["Id"],"values":[[2],[4]]}
+```