MySql 'window function‘和'DATEDIFF，怎么使用？

Question

我需要建立mysql查询。如果我使用该查询：

SELECT 
    Date, Time, EventId, UserId,
    Date - LEAD(Date) OVER W AS 'diff'
  FROM first
  WINDOW W AS (ORDER BY Date);

一切正常。但是我需要使用DATEDIFF()函数，比如：

SELECT      
    Date, Time, EventId, UserId, 
    DATEDIFF(Date, LEAD(Date)) OVER W AS 'diff'
  FROM first
  WINDOW W AS (ORDER BY Date);

但我现在有一个错误：

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') OVER W AS 'diff' FROM first WINDOW W AS (ORDER BY Date)'。那么如何使用DATEDIFF()函数呢？

答案是：

SELECT 
    Date, Time, EventId, UserId, 
    DATEDIFF(DATE, LEAD(Date) OVER W) AS 'diff' 
  FROM first 
  WINDOW W AS (ORDER BY Date);

Answer 1

答案是：

SELECT 
    Date, Time, EventId, UserId, 
    DATEDIFF(DATE, LEAD(Date) OVER W) AS 'diff' 
  FROM first 
  WINDOW W AS (ORDER BY Date);