如何计算CDS view里两个时间戳之间的天数间隔

ABAP透明表里的时间戳，数据类型为dec：

有个需求：计算这两个时间戳之间的天数间隔，丢弃时间戳年-月-日8位后面的小时：分钟：秒。

举个例子：如果时间戳是20180918173132，丢弃173132，只保留20180918, 然后再计算天数间隔。

直接用CDS view的字符串操作函数substring是不行的，因为时间戳类型dec和substring期待的字符串类型不匹配。

解决方案：

先将时间戳字段类型从dec强制转换成abap.dats：

@AbapCatalog.sqlViewName: 'zproday'

@AbapCatalog.compiler.compareFilter: true

@AccessControl.authorizationCheck: #CHECK

@EndUserText.label: 'Day between'

define view zdate_day_between as select from comm_product {

key comm_product.product_id as prod_id,

comm_product.product_guid as prod_guid,

comm_product.valid_from as valid_from,

comm_product.valid_to as valid_to,

cast(substring(cast(valid_from as abap.char(32)),1,8) as abap.dats) as from_date,

cast(substring(cast(valid_to as abap.char(32)),1,8) as abap.dats) as to_date

}

然后再用CDS view标准的时间处理函数DATS_DAYS_BETWEEN:

@AbapCatalog.sqlViewName: 'zdbetw'

@AbapCatalog.compiler.compareFilter: true

@AccessControl.authorizationCheck: #CHECK

@EndUserText.label: 'Day between'

define view zc_date_day_between as select from zdate_day_between as host{

key host.prod_guid,

host.prod_id,

host.from_date,

host.to_date,

DATS_DAYS_BETWEEN(host.from_date, host.to_date) as no_of_days

}

测试结果：

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