hive-ag真人游戏

• lead 分区的数据往前默认是往前一位

• lag 分区后的数据往后移动 

• first_value 取第一个值the second (optional) parameter must be a boolean which is false by default. if set to true it skips null values.如果第一个值是null那么如果是true那么就是跳过空值。

• last_value  最后的一个值the second (optional) parameter must be a boolean which is false by default. if set to true it skips null values.如果第二个数字是true那么就是，那么就是跳过空值

•  设置窗口的大小

• (rows | range) between (unbounded | [num]) preceding and ([num] preceding | current row | (unbounded | [num]) following)
  (rows | range) between current row and (current row | (unbounded | [num]) following)
  (rows | range) between [num] following and (unbounded | [num]) following

• unbounded preceding是窗口的上边界
• [num] preceding 是窗口的前几条或者是后几条
• current row 是当前的行
• unbounded following 是下边界
• [num] following 是下面几条

• order by 如果没有指定窗口那么就是range between unbounded preceding and current row

•  when both order by and window clauses are missing, the window specification defaults to row between unbounded preceding and unbounded following.

如果不指定order by 和窗口那么就是上边界和下边界

• 使用 rank

• 使用row_number

• 使用 dense_rank

• 使用 cume_dist 

• ntile 
•  

 percent_rank 计算方法为 (rank - 1)/(n- 1)