SQL to return the number of working days between 2 passed in dates

Question

I need to write an sql query that returns the number of Working days (Monday - Friday) between two given dates.

I was wondering what would be the most efficient way

Answer 1

Here is an example

with given_days(d) as(
  select <> + level - 1
    from dual
  connect by level < = (<> - <>) + 1
)
select count(*)
  from given_days
where to_char(d, 'DY', 'NLS_DATE_LANGUAGE=english') not in ('SUN', 'SAT')

Demonstration

HR\XE> with given_days as(
  2    select (to_date('&&1', 'dd.mm.yyyy') + level - 1) as g_day
  3      from dual
  4    connect by level < = (to_date('&2', 'dd.mm.yyyy') - to_date('&&1', 'dd.mm.yyyy')) + 1
  5  )
  6  select count(g_day) as cnt
  7    from given_days
  8  where to_char(g_day, 'DY', 'NLS_DATE_LANGUAGE=english') not in ('SUN', 'SAT');
Enter value for 1: 10.10.2012
old   2:   select to_date('&&1', 'dd.mm.yyyy') + level - 1
new   2:   select to_date('10.10.2012', 'dd.mm.yyyy') + level - 1
Enter value for 2: 17.10.2012
old   4:   connect by level < = (to_date('&2', 'dd.mm.yyyy') - to_date('&&1', 'dd.mm.yyyy')) + 1
new   4:   connect by level < = (to_date('17.10.2012', 'dd.mm.yyyy') - to_date('10.10.2012', 'dd.mm.yyyy')) + 1

  cnt                                                                     
----------                           
   6