分析函数
1、窗口函数(开窗函数),关键字:over
(0)基础知识
2 preceding ====== 前两行
2 following ====== 后两行
current row ====== 当前行
unbounded preceding ====== 无上限
unbounded following ====== 无下限
(1)表user_par的结构和数据如下图
(2)以行定义窗口界限
(2-1)按id排序,并计算当前行和以下两行的年龄之和
select id, name, age, sum(age)over(order by id rows between current row and 2 following) from user_par;
(2-2)按id排序,并计算当前行和以上两行的年龄之和
select id, name, age, sum(age)over(order by id rows between current row and 2 following) from user_par;