CREATE OR REPLACE FUNCTION count_row (start_date IN date)
RETURN  number as 
   n NUMBER;
   st date;
   s varchar2(256);
   begin
  st:=trunc(start_date);
  sq:=st;
  s:= 'select count(*)cc from PROIZVOD_CALENDAR pc where pc.HOLIDAY_INDICATOR=''Y''and pc.full_date=''02.01.2019'''; 
    execute immediate s INTO n;
  RETURN n;
end; 
/
with sss AS(select to_date('25.01.2019 18:30:52', 'DD.MM.YYYY HH24:MI:SS') as start_date, 
       to_date('30.01.2019 18:30:52', 'DD.MM.YYYY HH24:MI:SS') as end_date from dual)
SELECT T1.*, count_row(START_DATE)
FROM SSS T1;

CREATE OR REPLACE FUNCTION count_row (start_date IN date)
RETURN  number as 
   n NUMBER;
   st date;
   s varchar2(256);
   begin
  st:=trunc(start_date);
  sq:=st;
  s:= 'select count(*)cc from PROIZVOD_CALENDAR pc where pc.HOLIDAY_INDICATOR=''Y''and pc.full_date='||st;
    execute immediate s INTO n;
  RETURN n;
end; 
/
with sss AS(select to_date('25.01.2019 18:30:52', 'DD.MM.YYYY HH24:MI:SS') as start_date, 
       to_date('30.01.2019 18:30:52', 'DD.MM.YYYY HH24:MI:SS') as end_date from dual)
SELECT T1.*, count_row(START_DATE)
FROM SSS T1;

CREATE OR REPLACE FUNCTION net_time(start_date IN DATE, end_date IN DATE)
   RETURN NUMBER IS
busdays NUMBER := 0;
stDate DATE;
enDate DATE; 
st date;
et date;
sn number;
en number;
fn number;
pks varchar2(256);
pke varchar2(256);
pkf varchar2(256);
pks1 number;
pke1 number;
pkf1 number;
BEGIN 

stDate := start_date;
enDate := end_date;
st:=trunc(start_date);
et:=trunc(end_date);
pks:=q'[select count(*)cc from PROIZVOD_CALENDAR pc where pc.HOLIDAY_INDICATOR='Y' and pc.full_date=to_date(']'
||to_char(st,'dd.mm.yyyy')||q'[','dd.mm.yyyy')]';
execute immediate pks INTO pks1;
pke:=q'[select count(*)cc from PROIZVOD_CALENDAR pc where pc.HOLIDAY_INDICATOR='Y' and pc.full_date=to_date(']'
||to_char(et,'dd.mm.yyyy')||q'[','dd.mm.yyyy')]';
execute immediate pke INTO pke1;
pkf:=q'[select count(*)cc from PROIZVOD_CALENDAR pc where pc.HOLIDAY_INDICATOR='Y' and pc.full_date between to_date(']'
||to_char(st+1,'dd.mm.yyyy')||q'[','dd.mm.yyyy')]'||q'[and to_date(']'||to_char(et-1,'dd.mm.yyyy')||q'[','dd.mm.yyyy')]';
execute immediate pkf INTO pkf1;
if stDate<trunc(stDate)+7/24 and pks='0'
then sn:=14/24;
elsif 
  stDate>trunc(stDate)+21/24 or pks<>'0'
then sn:=0;
else
   sn := (trunc(stDate)+21/24)-stDate;
END IF;

if enDate<trunc(enDate)+7/24 or pke<>'0'
then en:=0;
elsif 
  enDate>trunc(enDate)+21/24 or pke='0'
then en:=14/24;
else
   en := enDate-(trunc(enDate)+7/24);
END IF;

fn:=(trunc(enDate)-trunc(stDate)-1-pkf1)*(14/24);
busdays:=decode(trunc(stDate),trunc(enDate),greatest((least(enDate,trunc(enDate)+21/24)-greatest(stDate,trunc(stDate)+7/24)),0),sn+en+fn);

   RETURN(fn);
END;

/
select net_time(start_date, end_date) as dddd
from (
select to_date('25.01.2019 10:10:00', 'DD.MM.YYYY HH24:MI:SS') as start_date, 
       to_date('30.01.2019 18:30:52', 'DD.MM.YYYY HH24:MI:SS') as end_date from dual);