SQL：如何用相同的值填充2个特定行之间的行？

Question

我需要用＆＃39;来填充/替换行。 - ＆＃39;在两个AL＆＃39;之间或两个＆＃39; MX＆＃39;价值＆＃39; AL＆＃39;或者＆＃39; MX＆＃39;取决于＆＃39; - ＆＃39;出现。出于这个例子的目的，我只使用2＆＃39; uid＆＃39; （我实际上有更多的uid）。此外，该表按ASC中的uid和code_date列进行排序

为了便于理解，我有这张表：

但我希望有这样的事情：

我正在使用SQL Server 2008.关于如何实现这一点的任何建议???

我使用以下代码创建了表：

DECLARE @Customers TABLE
    (uid bigint,
     code_date date,
     Value nchar(10)
    ) 

INSERT  INTO @Customers
VALUES  (1591, '2016-08-01', ''),
    (1591, '2016-08-02', ''),
    (1591, '2016-08-03', 'AL'),
    (1591, '2016-08-04', '-'),
    (1591, '2016-08-05', '-'),
    (1591, '2016-08-06', '-'),
    (1591, '2016-08-07', '-'),
    (1591, '2016-08-08', '-'),
    (1591, '2016-08-09', 'AL'),
    (1591, '2016-08-10', ''),
    (1591, '2016-08-11', 'AL'),
    (1591, '2016-08-12', ''),
    (1082, '2016-02-01', ''),
    (1082, '2016-02-02', ''),
    (1082, '2016-02-03', ''),
    (1082, '2016-02-04', ''),
    (1082, '2016-02-05', 'MX'),
    (1082, '2016-02-06', '-'),
    (1082, '2016-02-07', '-'),
    (1082, '2016-02-08', '-'),
    (1082, '2016-02-09', '-'),
    (1082, '2016-02-10', '-'),
    (1082, '2016-02-11', '-'),
    (1082, '2016-02-12', 'MX');

    SELECT * FROM @Customers ORDER BY uid, code_date ASC

Answer 1

+ scale_y_reverse()

Answer 2

declare @x varchar(1000) = ''

update @Customers
set  @x = value = (case when @x <> '' and value not in ('-',@x) then '' else @x end) + (case when value = '-' then '' when value = @x then ''  else value end)
where value <> ''

Answer 3

对于select查询，只需使用outer apply：

select t.*, coalesce(t.value, t2.value) as new_value
from t outer apply
     (select top 1 t2.*
      from t t2
      where t2.uid = t.uid and t2.code_date < t.code_date and t2.value is not null
      order by t2.code_date desc
     ) t2;

您可以在update中使用类似的逻辑。

作为update，这将是：

update t
    set value = t2.new_value
    from t outer apply
         (select top 1 t2.*
          from t t2
          where t2.uid = t.uid and t2.code_date < t.code_date and t2.value is not null
          order by t2.code_date desc
         ) t2
    where t.value is null;