pivot ora-56901

declare
  l_meas_for_dt NUMBER;
  l_meas_for_dt_am NUMBER;
  
  p_dt DATE := date'2015-01-01';
begin
 
  with w_t as (
    select date'2015-01-01' as dt, 100 meas from dual
    union all
    select date'2015-01-01' as dt, 200 meas from dual
    union all
    select date'2015-02-01' as dt, 200 meas from dual
    union all
    select date'2015-02-01' as dt, 300 meas from dual
    union all
    select date'2015-03-01' as dt, 400 meas from dual
    union all
    select date'2015-03-01' as dt, 500 meas from dual
  )
  select 
    dt,
    dt_am
  into l_meas_for_dt, l_meas_for_dt_am 
  from
    (select dt, meas from w_t)
  pivot(
    sum(meas) for dt in (
      /*p_dt as dt, --*/date'2015-01-01' as dt,
      /*add_months(p_dt, 1) as dt_am --*/add_months(date'2015-01-01', 1) as dt_am 
    )
  );
  
  dbms_output.put_line(l_meas_for_dt || ', ' || l_meas_for_dt_am); 
end;

declare
  l_meas_for_dt_am0 NUMBER;
  l_meas_for_dt_am1 NUMBER;
  l_meas_for_dt_am2 NUMBER;
  v_dt DATE := date'2015-01-01';
begin
  with w_t as (
    select date'2015-01-01' as dt, 100 as meas from dual union all
    select date'2015-01-01' as dt, 200 as meas from dual union all
    select date'2015-02-01' as dt, 200 as meas from dual union all
    select date'2015-02-01' as dt, 300 as meas from dual union all
    select date'2015-03-01' as dt, 400 as meas from dual union all
    select date'2015-03-01' as dt, 500 as meas from dual
  )
  select 
    sum(case when dt = add_months(v_dt, 0) then meas else 0 end), -- фиктивное выравнивание для повышения аккуратности :)
    sum(case when dt = add_months(v_dt, 1) then meas else 0 end),
    sum(case when dt = add_months(v_dt, 2) then meas else 0 end)
    /*...*/ 
  into l_meas_for_dt_am0, l_meas_for_dt_am1, l_meas_for_dt_am2
  from
    w_t;
  
  dbms_output.put_line(l_meas_for_dt_am0 || ', ' || l_meas_for_dt_am1 || ', ' || l_meas_for_dt_am2); 
end;