网站建网站建设设,网站主机哪买,山东最新新闻事件今天,自助建站软件公司目录 一、概念
1.rows between ... and ...
2.range between ... and ...
二、语法
1.关键词含义 一、概念
1.rows between ... and ...
rows#xff1a;指以行号来决定frame的范围#xff0c;是物理意义上的行。 2.range between ... and ...
range#xff1a;指以当…目录 一、概念
1.rows between ... and ...
2.range between ... and ...
二、语法
1.关键词含义 一、概念
1.rows between ... and ...
rows指以行号来决定frame的范围是物理意义上的行。 2.range between ... and ...
range指以当前行在开窗函数中的值为根基然后按照order by进行排序最后根据range去加减上下界。是逻辑意义上的行。 二、语法
(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
1.关键词含义
CURRENT ROW 表示当前行
UNBOUNDED PRECEDING 表示窗口的起始边界是窗口中第一行之前的无限行即初始行
UNBOUNDED FOLLOWING 表示窗口的起始边界是窗口中第一行之后的无限行即末尾行
UNBOUNDED 无边界
PRECEDING 往前
FOLLOWING 往后
(num) PRECEDING 表示当前行之前的num行。
(num) FOLLOWING 表示当前行之后的num行
