How to get Previous Value for Null Values

问题:

I have the Below Data in my Table.

   | Id  |  FeeModeId   |Name        |   Amount|
   ---------------------------------------------
   | 1   |  NULL        | NULL       |   20    |
   | 2   |  1           | Quarter-1  |   5000  |
   | 3   |  NULL        | NULL       |   2000  |    
   | 4   |  2           | Quarter-2  |   8000  |
   | 5   |  NULL        | NULL       |   5000  |
   | 6   |  NULL        | NULL       |   2000  |
   | 7   |  3           | Quarter-3  |   6000  |
   | 8   |  NULL        | NULL       |   4000  |

How to write such query to get below output...

   | Id  |  FeeModeId   |Name        |   Amount|
   ---------------------------------------------
   | 1   |  NULL        | NULL       |   20    |
   | 2   |  1           | Quarter-1  |   5000  |
   | 3   |  1           | Quarter-1  |   2000  |    
   | 4   |  2           | Quarter-2  |   8000  |
   | 5   |  2           | Quarter-2  |   5000  |
   | 6   |  2           | Quarter-2  |   2000  |
   | 7   |  3           | Quarter-3  |   6000  |
   | 8   |  3           | Quarter-3  |   4000  |

回答1:

Please try:

select 
    a.ID,
    ISNULL(a.FeeModeId, x.FeeModeId) FeeModeId,
    ISNULL(a.Name, x.Name) Name,
    a.Amount
from tbl a
outer apply
(select top 1 FeeModeId, Name 
    from tbl b 
    where b.ID<a.ID and 
        b.Amount is not null and 
        b.FeeModeId is not null and 
        a.FeeModeId is null order by ID desc)x

OR

select 
    ID,
    ISNULL(FeeModeId, bFeeModeId) FeeModeId,
    ISNULL(Name, bName) Name,
    Amount
From(
    select 
        a.ID , a.FeeModeId, a.Name, a.Amount, 
        b.ID bID, b.FeeModeId bFeeModeId, b.Name bName,
        MAX(b.FeeModeId) over (partition by a.ID) mx
    from tbl a left join tbl b on b.ID<a.ID
    and b.FeeModeId is not null
)x 
where bFeeModeId=mx or mx is null

回答2:

Since you are on SQL Server 2012... here is a version that uses that. It might be faster than other solutions but you have to test that on your data.

sum() over() will do a running sum ordered by Id adding 1 when there are a value in the column and keeping the current value for null values. The calculated running sum is then used to partition the result in first_value() over(). The first value ordered by Id for each "group" of rows generated by the running sum has the value you want.

select T.Id,
       first_value(T.FeeModeId) 
          over(partition by T.NF 
               order by T.Id 
               rows between unbounded preceding and current row) as FeeModeId,
       first_value(T.Name)      
          over(partition by T.NS 
               order by T.Id 
               rows between unbounded preceding and current row) as Name,
       T.Amount
from (
     select Id,
            FeeModeId,
            Name,
            Amount,
            sum(case when FeeModeId is null then 0 else 1 end) 
              over(order by Id) as NF,
            sum(case when Name is null then 0 else 1 end) 
              over(order by Id) as NS
     from YourTable
     ) as T

SQL Fiddle

Something that will work pre SQL Server 2012:

select T1.Id,
       T3.FeeModeId,
       T2.Name,
       T1.Amount
from YourTable as T1
  outer apply (select top(1) Name
               from YourTable as T2
               where T1.Id >= T2.Id and
                     T2.Name is not null
               order by T2.Id desc) as T2
  outer apply (select top(1) FeeModeId
               from YourTable as T3
               where T1.Id >= T3.Id and
                     T3.FeeModeId is not null
               order by T3.Id desc) as T3

SQL Fiddle

回答3:

try this -

SELECT Id,
       CASE
         WHEN Feemodeid IS NOT NULL THEN
          Feemodeid
         ELSE
          (SELECT Feemodeid
             FROM Table_Name t_2
            WHERE t_2.Id = (SELECT MAX(Id)
                              FROM Table_Name t_3
                             WHERE t_3.Id < t_1.Id
                               AND Feemodeid IS NOT NULL))
        END Feemodeid,
       CASE
         WHEN NAME IS NOT NULL THEN
          NAME
         ELSE
          (SELECT NAME
             FROM Table_Name t_2
            WHERE t_2.Id = (SELECT MAX(Id)
                              FROM Table_Name t_3
                             WHERE t_3.Id < t_1.Id
                               AND NAME IS NOT NULL))
       END NAME,
       Amount
  FROM Table_Name t_1

回答4:

SELECT
  T.ID,
  ISNULL(T.FeeModeId, 
    (SELECT TOP 1 FeeModeId 
        FROM TableName AS T1 
        WHERE ID < T.ID AND FeeModeId IS NOT NULL 
        ORDER BY ID DESC)) AS FeeModeId,
  ISNULL(Name,
    (SELECT TOP 1 Name 
    FROM TableName 
    WHERE ID < T.ID AND Name IS NOT NULL 
    ORDER BY ID DESC)) AS Name,
  T.Amount
FROM
  TableName AS T

回答5:

id  name
1   toto
2   NULL
3   NULL
4   titi
5   NULL
6   NULL
7   tutu
8   NULL
9   NULL


SELECT 
       id_table
       ,name
FROM 
       (
             SELECT
                    T_01.id AS 'id_table'
                    ,max(T_02.id) AS 'id_name'
             FROM
                    names AS T_01
                    cross join  
                    (
                          SELECT
                                 id
                                 ,name
                          FROM
                                 names
                          WHERE
                                 name IS NOT NULL
                    ) AS T_02 
             WHERE 
                    T_02.id <= T_01.id
             GROUP BY 
                    T_01.id
       ) AS tt02
       left join names
       ON names.id = tt02.id_name


id_table    name
1           toto
2           toto
3           toto
4           titi
5           titi
6           titi
7           tutu
8           tutu
9           tutu