如何在SQL中按两列匹配生成行号分区

Question

Tbl1

---------------------------------------------------------
Id      Date        Qty      ReOrder
---------------------------------------------------------
1       1-1-18      1        3
2       2-1-18      0        3
3       3-1-18      2        3
4       4-1-18      3<      >3
5       5-1-18      2        3
6       6-1-18      0        3
7       7-1-18      1        3
8       8-1-18      0        3
---------------------------------------------------------

我想要下面的结果

---------------------------------------------------------
Id      Date        Qty      ReOrder
---------------------------------------------------------
1       1-1-18      1        3
5       5-1-18      2        3
---------------------------------------------------------

如果ReOrder与Qty不相同，那么日期将保持不变，直到reorder = Qty

Answer 1

您可以将累积方法与MachineKeys函数一起使用：

row_number()

不幸的是，这需要 SQL Server ，但是您也可以这样做：

select top (1) with ties *
from (select *, max(case when qty = reorder then 'v' end) over (order by id desc) grp
      from table
     ) t
order by row_number() over(partition by grp order by id);