empty dates

    date    |  sum
------------+-------
 2011-04-29 | 34350
 2011-04-28 | 34650
 2011-04-27 | 34050
 2011-04-26 | 35550
 2011-04-25 | 34800
 2011-04-23 | 36750
 2011-04-22 | 37800
 2011-04-21 | 35550
 2011-04-20 | 35850
 2011-04-17 | 34050
 2011-04-16 | 36150
 2011-04-13 | 36450
 2011-04-11 | 32100
 2011-04-10 | 36600
 2011-04-09 | 41400
 2011-04-06 | 38100
 2011-04-05 | 35250
 2011-04-04 | 35400
 2011-04-03 | 36150
 2011-04-02 | 36000
 2011-04-01 |     0
 2011-03-31 | 36300
 2011-03-30 | 36300
 2011-03-25 | 37200

//query

select date(t_stamp), sum(total_charge) from mt.mt_batches where complete='t' and keyword='pablo'and date(t_stamp) between '2011-01-01' and '2011-04-30' group by date(t_stamp) order by date(t_stamp) desc;

//question
i want 0 value entered for the dates that are not there.
like this
   date    |  sum
------------+-------
  2011-04-30 | 0 (not present, has no value)
  2011-04-29 | 34350
 2011-04-28 | 34650
 2011-04-27 | 34050
 2011-04-26 | 35550
 2011-04-25 | 34800
 2011-04-23 | 36750
 2011-04-22 | 37800
 2011-04-21 | 35550
 2011-04-20 | 35850
 2011-04-19 | 0(not present, has no value)
 2011-04-18 | 0(not present, has no value)
 2011-04-17 | 34050
 2011-04-16 | 36150