sqlserver row_number() over() 理解

-- 創建語句
create table goodsTest(--商品表
    id int primary key identity(1,1),
    goosType varchar(100),--商品歸類
    goodsName varchar(100),--商品名稱
    serialNo int
)
go
insert into goodsTest(goosType,goodsName)
select '面類','面包' union
select '面類','燴面' union
select '飲品','礦泉水' union
select '飲品','冰紅茶' union
select '飲品','茶' union
select '面類','餄烙面' union
select '面類','雞蛋灌餅' union
select '面類','手抓餅' union
select '飲品','茶π' union
select '零食','脆司令' union
select '零食','勁仔小魚' union
select '零食','衛龍' 

--用法1.》》》row_number() over(Order by ...)
select row_number() over(order by goodsName) rownum,goodsName  from goodsTest --根據goodsName 排序得到連續的序號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 --根據 goosType 分組,goodsName 排序得到連續的序號rownum

--經常用法3.》》》 修改數據的序號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