Question

我需要找到分数从null变为非null的客户端（例如1,4,7）。我使用外部申请获得最近的分数，这是空的。我的SQL在下面，它不对。你能帮我解决一下吗？谢谢！

SELECT DISTINCT
CLT_NBR,
t.SCORE
FROM TABLE_CLIENT t
OUTER APPLY
( SELECT TOP 1 t2.SCORE
  FROM TABLE_CLIENT t2
  WHERE t2.CLT_NBR= t.CLT_NBR AND t2.START_DT<t.START_DT
  ORDER BY t2.START_DT DESC
  ) AS sprev
 WHERE t.SCORE IS NOT NULL 
    AND sprev.SCORE IS NULL

Answer 1

使用exists() :(如果以前的得分为null，则返回行）

select distinct 
    clt_nbr
  , score
from table_client t
where score is not null
  and exists (
    select 1
    from table_client i
    where i.clt_nbr = t.clt_nbr 
      and i.start_dt < t.start_dt
      and i.score is null
      )

使用cross apply() :(而不是outer apply()，因此我们不会获得没有上一行的行）

select 
    t.clt_nbr
  , t.score
from table_client t
  cross apply (
    select top 1 i.score
    from table_client i
    where i.clt_nbr = t.clt_nbr 
      and i.start_dt < t.start_dt
    order by i.start_dt desc
    ) as x
where t.score is not null 
  and x.score is null

使用lag()（SQL Server 2012+）:(返回最近一次得分为null的行）

with cte as (
    select  
        clt_nbr
      , score
      , start_dt
      , prev_score = lag(score) over (partition by clt_nbr order by start_dt)
      , prev_start_dt = lag(score) over (partition by clt_nbr order by start_dt)
    from table_client t
)
select 
    clt_nbr
  , score
from cte
where score is not null 
  and prev_score is null
  and prev_start_dt is not null

获得以前的分数

1 个答案: