sqlserver row_number() 分组序号

原表：

OrganizationID	itemprice
XX	A
XX	B
XX	C
YY	A
YY	B
YY	C
XY	A
XY	B

结果：

rownum	OrganizationID	itemprice
1	XX	A
2	XX	B
3	XX	C
1	YY	A
2	YY	B
3	YY	C
1	XY	A
2	XY	B

select row_number() over(partition by OrganizationID order by itemprice) rownum,* from Master_margin