如何获取前一行值 Teradata

Question

我有以下格式的数据

 Id    Code    Date         Amount       Type
 101   B25     5/4/2020      0         C
 101   A15     5/5/2020      0         D
 101   D15     5/5/2020      0         D
 102   B35     6/2/2020      0         C
 102   A15     6/2/2020                D

我需要以下内容

 Id    Code    Date         Amount       Type  C_Date          C_Amount
 101   A15     5/5/2020      0         D    5/4/2020         0
 102   A15     6/2/2020                D    6/2/2020         0

对于所有代码='A15'，我需要上一行的日期和金额，其中类型='C'

我做到了

 Select id, Amount, Date,
  sum(Amount) over (partition by ID ROWS between UNBOUNDED PRECEDING and CURRENT ROW) as 
   C_Amount,
  Max(Date) over (partition by ID ROWS between UNBOUNDED PRECEDING and CURRENT ROW) as 
   C_Date
 from Table
 where code='A15' or Type='C'

输出不是想要的

 Id    Code    Date         Amount       Type  C_Date          C_Amount
 101   A15     5/5/2020      0         D    ***5/5/2020         0***
 102   A15     6/2/2020                D    ***6/2/2020         ***

感谢任何帮助

Answer 1

答案集与您的查询不匹配，它也会包含 'C' 行。

ROWS between UNBOUNDED PRECEDING and CURRENT ROW是一个组和。

您需要 ROWS between 1 PRECEDING and 1 PRECEDNG 和一个 ORDER BY 来获取上一行的值。

最好切换到 LAG 或 LAST_VALUE，这更简单并且允许处理 'A15' 和前 'C' 行之间的额外行：

 Select id, Amount, Date,
  LAG(case when Type='C' then Amount end IGNORE NULLS)
  over (partition by ID
        order by date) as C_Amount,
  LAG(case when Type='C' then date end IGNORE NULLS)
  over (partition by ID
        order by date) as C_Date
 from Table
 where code='A15' or Type='C'
 qualify code='A15';

如何获取前一行值 Teradata

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