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如何设置窗口函数中窗口的大小

2022-04-22 05:55:00 【大大大大肉包】 

当我们不设置窗口的大小时候，默认窗口大小为首行到当前行


rows between unbounded preceding and current row

select count(*) over(partition by col1) from tmp_test;

select count(*) over(partition by order by  rows between unbounded preceding and current row) from tmp_test;

这俩个语句是等价的

可以对以下关键字就行搭配使用

between CURRENT ROW | UNBOUNDED PRECEDING | [num] PRECEDING 

 AND UNBOUNDED FOLLOWING | [num] FOLLOWING| CURRENT ROW

例如：

首行到尾行

select count(*) over(partition by order by  rows between unbounded preceding and UNBOUNDED FOLLOWING ) from tmp_test;

前一行到下一行

select count(*) over(partition by order by  rows between 1 preceding and 1 following) from tmp_test;

版权声明
本文为[大大大大肉包]所创，转载请带上原文链接，感谢
https://blog.csdn.net/qq_42456324/article/details/120197615

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