mysql - CASE w/ DATEADD range to SUM column multiple times for future earnings estimate -

edit: original post follows, bit long , wordy. edit presents simplified question.

i'm trying sum 1 column multiple times; i've found, options either case or (select). trying sum based on date range , can't figure out if case allows that.

 table.number  |  table.date      2        2014/12/18    2        2014/12/19    3        2015/01/11    3        2015/01/12    7        2015/02/04    7        2015/02/05 

as separate queries, this:

select sum(number) alpha table date >= 2014/12/01 , date<= date_add (2014/12/01, interval 4 weeks) select sum(number) beta table date >= 2014/12/29 , date<= date_add (2014/12/01, interval 4 weeks) select sum(number) gamma table date >= 2014/01/19 , date<= date_add (2014/12/01, interval 4 weeks) 

looking result set

alpha   |   beta   | gamma   2          6         14 

original: i'm trying return sum of payments due within budgeting time frame (4 weeks) current budgeting period , 2 future periods. students pay every 4 weeks, others every 12. here relevant fields in tables:

client.name |   client.ppid |  client.last_payment john            |   1       |   12/01/14 jack            |   2       |   11/26/14 jane            |   3       |    10/27/14           pay_profile.id  | pay_profile.price | pay_profile.interval  (in weeks)         1                   140                     4         2                   399                     4         3                   1                       12  pay_history.name    |   pay_history.date  | pay_history.amount  john                |       12/02/14      |        140 jerry               |   more historical   |       data   budget.period_start |         12/01/14 

i think efficient way of doing is:

1.)sum students pay every 4 weeks base_pay

2.)sum students pay every 12 weeks , dateadd(client.last_payment, interval pay_profile.interval weeks) >= budget.period_start , <= dateadd(budget.period_start, interval 28 days) accounts_receivable

3.) above step miss people who've paid in budgeting period (as updates last_payment dating, putting them out of range specified in #2), i'll need sum pay_history.date range above well. paid_in_full

4.) repeat step 2 above, adjusting range , column name future periods (i.e. accounts_receivable_2

5.) use php sum base_pay, accounts_receivable, , pay_history, repeating process future periods.

i'm guessing easiest way use case, i've not done before. here best guess, fails due sytax error. assuming can use date_add in when statement.

select  case      date_add(client.last_payment, interval pay_profile.interval week) >= budget.period_start      ,      date_add(client.last_payment, interval pay_profile.interval week) <=                                                                date_add(budget.period_start,interval 28 day) sum(pay_profile.price) base_pay client left outer join pay_profile on client.ppid = pay_profile.ppid  left outer join budget on client.active = 1 client.active = 1  

thanks.