select dt, 
       count( 1 )      as counter,
       sum(less_30)  as sum_less_30,
       sum(less_50)  as sum_less_50,
       sum(less_100) as sum_less_100
  from (
          select trunc(data) /*
                                 TRUNC - в Oracle это функция усечения порции времени в дате,
                                 Аналог такой функции в PostgrеSQL подбери сам, я его не знаю
                             */
                   as dt,
                 case 
                    when id <  30  then  1 
                    else  0 
                 end as less_30,
                 case
                    when id >=  30  and id <  50  then  1 
                    else  0 
                 end less_50,
                 case
                    when id >=  50  and id <  100  then  1 
                    else  0 
                 end as less_100
            from "ТВОЯ_ТАБЛИЦА"
       )
group by dt

Query finished, retrieving results...

     DT      COUNTER  SUM_LESS_30  SUM_LESS_50  SUM_LESS_100
-----------  -------  -----------  -----------  ------------
 14 -дек- 2005          2              1              1               0 
 15 -дек- 2005          1              0              0               1 
 16 -дек- 2005          4              1              1               2 

 3  row(s) retrieved