Вы можете использовать порядок по месяцам ()
select
SUM(montant_ht)as Achat
,monthname(dim_date.date) as mois
from operation_odoo
join dim_date on operation_odoo.id_date_facturation = dim_date.id_date
where (operation_odoo.id_type_op=1) and (dim_date.Annee= ? or ? is null )
group by mois
order by month(dim_date.date)
для SpagoBI, попробуйте добавить также столбец month () к запросу
select
SUM(montant_ht)as Achat
,monthname(dim_date.date) as mois
, month(dim_date.date)
from operation_odoo
join dim_date on operation_odoo.id_date_facturation = dim_date.id_date
where (operation_odoo.id_type_op=1) and (dim_date.Annee= ? or ? is null )
group by mois, month(dim_date.date)
order by month(dim_date.date)