How to get Previous Value for Null Values - sql

Question

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 |

Answer 1

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

Answer 2

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

Answer 3

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

Answer 4

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

Answer 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