上升的温度

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。

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+---------+------------------+------------------+
| 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:

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+----+
| Id |
+----+
|  2 |
|  4 |
+----+

解题思路

  1. DATEDIFF该函数求两个日期的天数差(执行时间太长)
  2. TO_DAYS

代码

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SELECT w1.`Id` FROM weather w1,weather w2 
WHERE 
DATEDIFF(w1.`RecordDate`,w2.`RecordDate`)=1 
AND 
w1.`Temperature`>w2.`Temperature`
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SELECT w1.`Id` FROM weather w1,weather w2 
WHERE 
TO_DAYS(w1.`RecordDate`)-TO_DAYS(w2.`RecordDate`)=1 
AND 
w1.`Temperature`>w2.`Temperature`