[英]Get count of distinct key field values from CDS
I would like to ask if it is possible to get dynamically Count of distinct fields using ABAP.我想问一下是否可以使用 ABAP 动态获取不同字段的计数。
Key in our CDS has 9 fields which is quite a lot but it is not possible to split because of historical decisions.我们的 CDS 中的 key 有 9 个字段,数量很多,但由于历史决定,无法拆分。 What I need is code like below:
我需要的是如下代码:
select count(distinct (lv_requested_elements)) from CDS_VIEW;
or或者
select count(*) from (select distinct lv_requested_elements from CDS_VIEW);
I know that it is possible to read the select into memory and get sy-dbcnt
but I want to be sure that there is no other option.我知道可以将 select 读入 memory 并获得
sy-dbcnt
但我想确定没有其他选择。
I assume that most simple and straightforward way is to read the smallest field into memory and then count by grouped (distinctified) rows:我假设最简单直接的方法是将最小字段读入 memory 然后按分组(区分)行计数:
DATA(fields) = ` BLART, BLDAT, BUDAT`.
DATA: lt_count TYPE TABLE OF string.
SELECT (fields(6))
INTO TABLE @lt_count
FROM ('BKPF')
GROUP BY (fields).
DATA(count) = sy-dbcnt.
CTE , that was mentioned, uses the same memory read, so you'll receive no performance gain:前面提到的CTE使用相同的 memory 读取,因此您不会获得任何性能提升:
A common table expression creates a temporary tabular results set, which can be accessed during execution of the WITH statement
公用表表达式创建一个临时表格结果集,可在 WITH 语句执行期间访问
If you going to count this key combination frequently, I propose to create consumption or nested CDS view which will do this on-the-fly.如果您要经常计算此组合键,我建议创建消费或嵌套 CDS 视图,它会即时执行此操作。
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