SQL Server query for merging 2 rows in 1

Question

There is a SQL Server table (see the screenshot below) that I cannot change:

Products have identifiers and process parameters. There are 2 processes, A and B. Every process stores data in an own row.

I would like to get a table result without useless NULL values. One product on one row, no more. Desired cells are highlighted. See the 2nd screenshot for the desired output:

Answer 1

select a.id,
       isnull(b.state,   a.state)   as state,
       isnull(b.process, a.process) as process,
       isnull(b.length,  a.length)  as length,
       isnull(b.force,   a.force)   as force,
       isnull(b.angle,   a.angle)   as angle
 from      table as a 
 left join table as b 
   on a.id = b.id   
  and b.process = 'B'
where a.process = 'A' 


DECLARE @T AS TABLE (id int, state varchar(10), process varchar(10), length int, angle int  
                     primary key (id, process));
insert into @t (id, state, process, length, angle)  values
      (111, 'OK',  'A', 77, null)
     ,(111, 'OK',  'B', null, 30)
     ,(159, 'NOK', 'A', 89, null)
     ,(147, 'OK',  'A', 78, null)
     ,(147, 'NOK', 'B', null, 36);

select ta.id, --ta.*, tb.*
       isnull(tb.state,   ta.state)   as state,
       isnull(tb.process, ta.process) as process,
       isnull(tb.length,  ta.length)  as length, 
       isnull(tb.angle,   ta.angle)   as angle
 from @t ta 
 left join @t tb 
   on ta.id = tb.id   
  and tb.process = 'B' 
where ta.process = 'A' 
order by ta.id 

Answer 2

Self join? (edited)

so,

select
 a.id,
 a.process,
 isnull(a.length, b.length) as length,
 isnull(a.force, b.force) as force,
 isnull(a.angle, b.angle) as angle
from
 (select * from tmpdel where process = 'A') as a left join
 (select * from tmpdel where process = 'B') as b on
 a.id = b.id

I've given this a quick test and I think it looks right.