前言

将mysql 的累加求和计算方式改写为达梦写法，mysql是通过变量相加的方式实现了

mysql写法

SELECT id , name , age , 
	(@age:=@age + age ) as  age_sum
FROM user , ( SELECT @age := 0  ) s
ORDER BY id 

达梦写法

SELECT id , name , age ,
sum(age) OVER (ORDER BY id asc) AS ageRank
FROM user