如何根据其他列组获取行数

Question

我需要计算每个月向某些客户开具发票的日期数

考虑名为 Table1

的 table

Branch  Month  Date     Amount
----------------------------------------
 B1     April  01/04/20  10000
 B1     April  14/04/20  13000
 B1     May    01/05/20  25000
 B1     May    14/05/20  23000

我尝试了以下代码

Select 
    Branch, Month, Date, Amount,
    Row_Number() over (partition by Branch order by Month) as rowcount 
from table1

结果是

Branch  Month  Date      Amount   rowcount
----------------------------------------
 B1     April  01/04/20  10000      1
 B1     April  14/04/20  13000      2
 B1     May    01/05/20  25000      3
 B1     May    14/05/20  23000      4

我需要的结果应该是根据列month来统计branch的列，想要的结果是

Branch  Month  Date      Amount   rowcount
---------------------------------------------
 B1     April  01/04/20  10000     1
 B1     April  14/04/20  13000     2
 B1     May    01/05/20  25000     1
 B1     May    14/05/20  23000     2

这里rowcount是根据column branch和Month来计算的，请问如何得出这个结果？

Answer 1

您需要按 month 进行分区。像这样：

row_number() over (partition by Branch, month order by Month)

注意month重复了。 SQL 服务器需要 order by，因此您需要东西。其他选项是：

row_number() over (partition by Branch, month order by (select null))
row_number() over (partition by Branch, month order by date)

我怀疑最后一个才是你真正想要的。

如何根据其他列组获取行数

How to get row count based on other column groups

sql

sql-server

group-by

rowcount