ejemplo, PostgreSQL

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create table aux (
    month_id integer, 
    year_id integer, 
    id integer, 
    concept text, 
    "value" numeric
);

insert into aux values
  (201612, 2016, 1234, 'A', 1),
  (201612, 2016, 1234, 'B', 2),
  (201612, 2016, 1234, 'C', 0),
  (201612, 2016, 1234, 'D', 3),
  (201612, 2016, 1234, 'A', 1),
  (201612, 2016, 1234, 'B', 2),
  (201612, 2016, 1234, 'C', 0),
  (201612, 2016, 1234, 'D', 3),
  (201701, 2017, 1234, 'A', 2),
  (201701, 2017, 1234, 'B', 3),
  (201701, 2017, 1234, 'C', 0),
  (201701, 2017, 1234, 'D', 4),
  (201701, 2017, 1234, 'A', 2),
  (201701, 2017, 1234, 'B', 3),
  (201701, 2017, 1234, 'C', 0),
  (201701, 2017, 1234, 'D', 4),
  (201702, 2017, 1234, 'A', 5),
  (201702, 2017, 1234, 'B', 6),
  (201702, 2017, 1234, 'C', 0),
  (201702, 2017, 1234, 'D', 1),
  (201702, 2017, 1234, 'A', 5),
  (201702, 2017, 1234, 'B', 6),
  (201702, 2017, 1234, 'C', 0),
  (201702, 2017, 1234, 'D', 1);

SELECT year_id, id, concept,
CASE WHEN concept <> 'C' THEN SUM(CASE WHEN month_id = 201701 then value else 0 end) 
						 ELSE SUM(CASE WHEN month_id = 201612 and concept = 'B' then value else 0 end)end as Jan,
                         
CASE WHEN concept <> 'C' THEN SUM(CASE WHEN month_id = 201702 then value else 0 end) 
						 ELSE SUM(CASE WHEN month_id = 201701 and concept = 'B' then value else 0 end)end as Feb,
                         
CASE WHEN concept = 'C' THEN SUM(CASE WHEN month_id = 201701 and concept = 'B' then value else 0 end) else 0 end as Mar
from aux 
group by year_id, id, concept
order by year_id, id, concept;


absolute service time: 0,46 sec