使用 on 条件过滤同一列两次的行

Question

我有下一个查询：

        select CHANNEL , my_date 
        from table_1 d
        where source_data = 'test_5'
          and my_date < to_date('27/09/2020','DD/MM/YYYY')
          and customer_ID = :param_customer_ID
        order by d.my_date asc;

这将显示下一个结果：

我的需求是。对最后一个 my_date 使用最后一个值过滤器，按通道分组。此示例的结果必须如下所示：

只有两行。

我试过：

select CHANNEL , my_date 
from table_1 d
where source_data = 'test_5'
  and (my_date < to_date('27/09/2020','DD/MM/YYYY') and my_date = max(my_date))
  and customer_ID = :param_customer_ID
group by CHANNEL, my_date 
order by d.my_date asc;

但是没有，它不起作用，给我报错

ORA-00934: función de grupo no permitida aquí
00934. 00000 -  "group function is not allowed here"
*Cause:    
*Action:
Error en la línea: 138, columna: 30

我该怎么办？

此致

Answer 1

在 Oracle 中，您可以使用聚合：

select channel, max(my_date)
from table_1 d
where source_data = 'test_5' and
      my_date < date '2020-09-27' and
      customer_ID = :param_customer_ID
group by channel;

如果您需要更多列，请使用 row_number():

select channel, my_date
from (select d.*,
             row_number() over (partition by channel order by my_date desc) as seqnum
      from table_1 d
      where source_data = 'test_5' and
            my_date < date '2020-09-27' and
            customer_ID = :param_customer_ID
     ) d
where seqnum = 1;

使用 on 条件过滤同一列两次的行

Filter rows using on conditions twice the same column

sql

plsql

oracle-sqldeveloper

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