Update table without using a cursor

Hi,

I have a table that looks something like this:

Id                   Col1             col2
1                    H123            Sooners  
2                    H222            Buckeyes
3                    (null)             (null)
4                    (null)             (null)
5                    H234            Gators
6                    (null)            (null)
7                    H566           Ducks
8                    H578           Longhorns


is there a way to replace the null values with values from the previous row that is not null without having to resort to cursors so that the table ends up something like this:

Id                   Col1            col2
1                    H123            Sooners  
2                    H222            Buckeyes
3                    H222            Buckeyes
4                    H222            Buckeyes
5                    H234            Gators
6                    H234            Gators
7                    H566            Ducks
8                    H578            Longhorns
LVL 1
yechanAsked:
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Christopher GordonSenior Developer AnalystCommented:
Here is my crack at it.  I'm interested to see if there are other responses.

See attachment for testing code that will run in Management Studio


--hold number of nulls
declare @myNulls smallint

--inital number of null values
select      @myNulls = COUNT(*)
from      @myTable
where      Col2 is null

--update from previous row until NULL values are gone
while isnull(@myNulls,0) > 0
begin

      update @myTable
      set            
            Col2 = isnull(a.Col2, (select Col2 from @myTable b where b.Id = (a.Id - 1)))
      ,      Col1 = isnull(a.Col1, (select Col1 from @myTable b where b.Id = (a.Id - 1)))

      from @myTable a

      --get count of remamining nulls
      select @myNulls = COUNT(*)
      from      @myTable
      where      Col2 is null

end

select      *
from      @myTable
update-nulls.sql
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yechanAuthor Commented:
This is really great.  Thanks.  I am going to leave this question open for a little while longer per your suggestion as to see what others come up with.

again.  thanks.
0
Christopher GordonSenior Developer AnalystCommented:
Yes, leave it open, I'm interested to see if there is a solution that can pull this off without using a while loop.  I'm thinking that there probably is.
0
yechanAuthor Commented:
gohord, I am going ahead and close this ticket.  I have implemented your solution and it works great.

ty.
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Microsoft SQL Server 2008

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