之前用过row_number(),rank()等排序与over( partition by ... ORDER BY ...),这两个比较好理解: 先分组,然后在组内排名. 今天突然碰到sum(...) over( partition by ... ORDER BY ... ),居然搞不清除怎么执行的,所以查了些资料,做了下实操. 1. 从最简单的开始 sum(...) over( ),对所有行求和 sum(...) over( order by ... ),和 = 第一行 到 与当前行同序号…
Your environment has been set up for using Node.js 8.5.0 (x64) and npm. C:\Users\horn1>cd C:\Users\horn1\Desktop\python\42-torrentParser C:\Users\horn1\Desktop\python\42-torrentParser>python torrentParser.py 文件名=./6.torrent 文件结构: announce:b'http://t…
ROWNUMBER() OVER( PARTITION BY COL1 ORDER BY COL2)用法 今天在使用多字段去重时,由于某些字段有多种可能性,只需根据部分字段进行去重,在网上看到了rownumber() over(partition by col1 order by col2)去重的方法,很不错,在此记录分享下: row_number() OVER ( PARTITION BY COL1 ORDER BY COL2) 表示根据COL1分组,在分组内部根据 COL2排序,而此函数计算…
题意:一个n*m的矩阵,要么是 . 要么是 z ,问可以形成几个大z 分析:(直接奉上官方题解,我感觉说的实在是太好了) Let's precalculate the values zlij, zrij, zldij — the maximal number of letters 'z' to the left, to the right and to the left-down from the position (i, j). It's easy to do in O(nm) time. L…
sum(x) over( partition by y ORDER BY z ) 分析 sum(x) over (partition by y order by z) 求安照y分区,然后按z排序,连续加当前顺序号前面的数值 (求每个分区中,按照z的顺序累计求和) a b 1 2 3 4 5 6 sum(b) over (order by a) a b sum 1 2 1 3 4 1+3 5 6 1+3+5 sum(b) over (order by a desc ) a b sum…