How can I fill the null values with the values up these nulls

Question

How can I fill the null values with the values below these null values?

Example, I have a table like this:

Mat   Name
123   Jerry
Null  Mary
Null  Sam
45         


        

Answer 1

If you are able to add an ID column to your table (if you don't have one already) this query should work

declare @tbl as table (
    id int
    ,mat int
    ,name varchar(15)
)

insert into @tbl values (1,123, 'Jerry')
insert into @tbl values (2,NULL, 'Marry')
insert into @tbl values (3,NULL, 'Sam')
insert into @tbl values (4,456, 'Matt')
insert into @tbl values (5,NULL, 'Harry')
insert into @tbl values (6,NULL, 'Jin')

SELECT
    id
    ,CASE WHEN
        mat IS NULL THEN
            (SELECT TOP 1 mat FROM @tbl WHERE id