Teradata 递归更新

Question

我有这样的数据记录，我想从以前的填充记录更新空白记录 enter image description here

ID  L_nbr   Code    Descripton
t001    5   S001    ABCDE
t001    12  S002    FGHI
t001    15          JKM
t001    17          NOPE
t001    18  S003    RST
t001    19          UVW
t001    21  S004    ASDS34E
t001    24          GTUS
t001    27          UNIF

预期数据如下

ID  L_nbr   Code    Descripton
t001    5   S001    ABCDE
t001    12  S002    FGHI
t001    15  S002    JKM
t001    17  S002    NOPE
t001    18  S003    RST
t001    19  S003    UVW
t001    21  S004    ASDS34E
t001    24  S004    GTUS
t001    27  S004    UNIF

请帮助我使用 Teradata 激活上述结果

谢谢

Answer 1

我认为 Aster 不支持 lag() 上的 ignore nulls 选项。因此，您可以分两步完成此操作。使用累积和定义 "islands"。然后把值散布到周围：

select t.*, max(code) over (partition by t_id, grp) as imputed_code
from (select t.*,
             count(code) over (partition by t_id
                               order by l_nbr
                               rows between unbounded preceding and current row
                              ) as grp
      from t
     ) t

Teradata 递归更新

Teradata update recursively

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