sqlserver row_number() over() 理解

-- 创建语句
create table goodsTest(--商品表
    id int primary key identity(1,1),
    goosType varchar(100),--商品归类
    goodsName varchar(100),--商品名称
    serialNo int
)
go
insert into goodsTest(goosType,goodsName)
select '面类','面包' union
select '面类','烩面' union
select '饮品','矿泉水' union
select '饮品','冰红茶' union
select '饮品','茶' union
select '面类','饸烙面' union
select '面类','鸡蛋灌饼' union
select '面类','手抓饼' union
select '饮品','茶π' union
select '零食','脆司令' union
select '零食','劲仔小鱼' union
select '零食','卫龙' 

--用法1.》》》row_number() over(Order by ...)
select row_number() over(order by goodsName) rownum,goodsName  from goodsTest --根据goodsName 排序得到连续的序号rownum

--用法2.》》》row_number() over(partition by ... Order by ...)
select row_number() over(partition by goosType order by goodsName) rownum,goodsName  from goodsTest --根据 goosType 分组,goodsName 排序得到连续的序号rownum

--经常用法3.》》》 修改数据的序号serialNo
update a set serialNo=b.RowNum
from  goodsTest a,
(select ROW_NUMBER() over(partition by goosType order by goodsName) RowNum,id from goodsTest /*where ID=''*/) b
where a.id=b.id