replace NULL values with latest non-NULL value in resultset series (SQL Server 2008 R2)

Question

for SQL Server 2008 R2

I have a resultset that looks like this (note [price] is numeric, NULL below represents a NULL value, the result set is ordered by product_i

Answer 1

I have a table containing the following data. I want to update all nulls in salary columns with previous value without taking null value.

Table:

id  name    salary
1   A       4000
2   B   
3   C   
4   C   
5   D       2000
6   E   
7   E   
8   F       1000
9   G       2000
10  G       3000
11  G       5000
12  G   

here is the query that works for me.

select a.*,first_value(a.salary)over(partition by a.value order by a.id) as abc from
(
     select *,sum(case when salary is null then 0 else 1 end)over(order by id) as value from test)a

output:

id  name    salary  Value   abc
1   A       4000    1     4000
2   B               1     4000
3   C               1     4000
4   C               1     4000
5   D       2000    2     2000
6   E               2     2000
7   E               2     2000
8   F       1000    3     1000
9   G       2000    4     2000
10  G       3000    5     3000
11  G       5000    6     5000
12  G               6     5000