嵌套案例语句Teradata将时间戳（0），时间戳（6）转换为日期并进行比较

Question

  I want to generate qualify_flag as '1' always when device_end_dt = '9999-12-31 23:29:59'. If it is 
 not '9999-12-31 23:29:59' then if DEVICE_END_DT + 1 day = CREATION_DATE then qualify_flag is 0 else 1. 
DEVICE_END_DT is TIMESTAMP(0), CREATION_DATE  is TIMESTAMP(6). 
CREATION_DATE column doesn't have any value which is '9999-12-31'.

下面的case语句由于日期无效而失败，似乎以某种方式出现了'9999-12-31'和（'9999-12-31'+ 1）不明确。

select
case When 
        Cast(DEVICE_END_DT AS DATE) <> CAST('9999-12-31' AS DATE) 
            THEN
                case when CAST((Cast(DEVICE_END_DT AS DATE) + 1) AS DATE) = Cast(CREATION_DATE AS DATE)
                        then 0
                        else 1
                end

case when   
        Cast(DEVICE_END_DT AS DATE) = CAST('9999-12-31' AS DATE) 
            THEN
                            1 
end 
end as qualify_flag
 FROM ABC;

Answer 1

这是简化的逻辑：

CASE 
  WHEN Cast(DEVICE_END_DT AS DATE) = Cast(CREATION_DATE AS DATE) - 1
  THEN 0
  ELSE 1
END

顺便说一句，最好使用日期文字 DATE '9999-12-31'代替CAST('9999-12-31' AS DATE)。

您要解决的最后一个业务问题是什么？看起来像在缓慢变化的维度 ..>中识别不良数据。