SQL Server : stretch values to emptly cells - sql

Question

I have problem with my table which look like this:
TABLE_XY
Dog
NULL
NULL
NULL
NULL
NULL
NULL
cat
NULL
NULL
NULL
Frog
..
I need from my table
dog
dog
dog
dog
dog
dog
cat
cat
cat
cat
cat
frog
frog
…
Do you know script which will stretch values to empty cells work my same like in excel. I cannot do manually because I have over 1 million rows..
My opinion is > UPDATE column name when exist value extend down to next..
Thank for help

Answer 1

Assuming you have a column that specifies each row, you can do this using apply:
update t
set t.col = tt.col
from yourtable t cross apply
(select top 1 t2.*
from yourtable t2
where t2.id < t.id and t2.col is not null
order by t2.id desc
) tt
where t.col is null;

Answer 2

If you have a column to order these results by
with CTE as
(
select Column1, row_number() over (order by OrderingColumn) as rn
from TableXYZ
)
select coalesce (x1.Column1, x2.Column1) as Column1
from CTE x1
left join CTE x2
on x2.rn = x1.rn+1

Answer 3

Assuming you have a column (let's say id) for ordering, you can execute the following query:
UPDATE table t
SET t.value = (
SELECT value FROM table WHERE id = (
SELECT MAX(id) FROM table WHERE id <= t.id AND value IS NOT NULL
)
)
WHERE t.value IS NULL;

Answer 4

The following solution will work, but the only caveat is that it might take a while to process all the million rows
declare #tempTable table
(
Animal varchar(100)
)
insert into #tempTable
(Animal)
values
('Dog'),
(NULL),
(NULL),
('Cow'),
(NULL),
(NULL),
(NULL),
('cat'),
(NULL),
('Sheep'),
(NULL),
('Frog'),
(null),
('Buffalo')
declare #animal varchar(100)
declare #notNullAnimal varchar(100)
declare animalCursor cursor for
select animal
from #tempTable
open animalCursor
while (1=1)
begin
fetch next from animalCursor into #animal
if(#animal is not null)
begin
set #notNullAnimal = #animal
end
else
begin
if(##FETCH_STATUS <> 0) break;
update #tempTable
set Animal = #notNullAnimal
where current of animalCursor
end
if(##FETCH_STATUS <> 0) break;
end
close animalCursor
deallocate animalCursor
select * from #tempTable

Answer 5

I have a SSIS solution for this problem which is part of the SQL Server family.
It's pretty easy.
I used a SQL Statement to generate your sample and you can see it as animal in the data viewer.
The work is done in a very short script component. Code below (Note the setup of variable outside of the ProcessInputRow):