Hmmm. Si j'interprète "les quatre derniers trimestres" comme "les quatre derniers trimestres qui sont dans les données", alors voici une méthode.
Tout d'abord, vous pouvez obtenir les quatre quarts en faisant :
select distinct p_year, p_quarter
from production p
order by p_year desc, p_quarter desc
limit 4;
Vous pouvez les énumérer à l'aide de variables :
select p_year, p_quarter, (@rn := @rn + 1) as enum
from (select distinct p_year, p_quarter
from production p
order by p_year desc, p_quarter desc
limit 4
) p cross join
(select @rn := 0) params
Ensuite, vous pouvez l'utiliser dans une requête pour faire pivoter les données :
select p.person_id,
sum(case when seqnum = 1 then num else 0 end) as num_quarter_1,
sum(case when seqnum = 2 then num else 0 end) as num_quarter_2,
sum(case when seqnum = 3 then num else 0 end) as num_quarter_3,
sum(case when seqnum = 4 then num else 0 end) as num_quarter_4
from production p join
(select p_year, p_quarter, (@rn := @rn + 1) as seqnum
from (select distinct p_year, p_quarter
from production p
order by p_year desc, p_quarter desc
limit 4
) p cross join
(select @rn := 0) params
) yq
using (p_year, p_quarter)
group by p.person_id;
MODIFIER :
Si vous définissez les trimestres en fonction du trimestre en cours, vous pouvez faire quelque chose d'assez similaire :
select p.person_id,
sum(case when seqnum = 1 then num else 0 end) as num_quarter_1,
sum(case when seqnum = 2 then num else 0 end) as num_quarter_2,
sum(case when seqnum = 3 then num else 0 end) as num_quarter_3,
sum(case when seqnum = 4 then num else 0 end) as num_quarter_4
from production p join
(select year(curdate()) as p_year, quarter(curdate()) as p_quarter, 1 as seqnum union all
select year(curdate() - interval 1 quarter) as p_year, month(curdate() - interval 1 quarter) as p_quarter, 2 as seqnum union all
select year(curdate() - interval 2 quarter) as p_year, month(curdate() - interval 2 quarter) as p_quarter, 3 as seqnum union all
select year(curdate() - interval 2 quarter) as p_year, month(curdate() - interval 3 quarter) as p_quarter, 4 as seqnum
) yq
using (p_year, p_quarter)
group by p.person_id;
Il existe d'autres approches, telles que :
select person_id,
sum(case when year(curdate()) = p_year and quarter(curdate()) = p_quarter
then num else 0
end) as num_quarter_1,
sum(case when year(curdate() - interval 1 quarter) = p_year and quarter(curdate() - interval 1 quarter) = p_quarter
then num else 0
end) as num_quarter_2,
sum(case when year(curdate() - interval 2 quarter) = p_year and quarter(curdate() - interval 2 quarter) = p_quarter
then num else 0
end) as num_quarter_3,
sum(case when year(curdate() - interval 3 quarter) = p_year and quarter(curdate() - interval 3 quarter) = p_quarter
then num else 0
end) as num_quarter_4
from production p
group by person_id;