php - Sum the value in if/else mysql select statement -

not sure how max date inside if/else statement of mysql query.

here select statement:

select month(max(a.planned_date))                     month,         a.planned_date                                 date,         year(max(a.planned_date))                      year,         sum(if(month(a.planned_date) = 1, b.value, 0)) jan,         sum(if(month(a.planned_date) = 2, b.value, 0)) feb,         sum(b.value)                                   total    b         inner join                 on b.id = a.id         inner join c                 on b.reg_id = c.reg_id   year(a.planned_date) < date(now())  group  c.reg_id  

all trying have cross table of jan dec, return max date bring value. however, way have done value doubling value.

please advise appreciated.

thank you