Query to group dates based on days of week

Question

Hi,
I have a table containing the following format:
Create table testtable(dates date, day_identifier number);
The day_identifier column data contains the corresponding dates columns' day of week equivalent i.e.
to_char(dates, 'd')
The table contains following sample data:
Dates
Day_identifier
01-Oct-2013
3
02-Oct-2013
4
04-Oct-2013
6
06-Oct-2013
1
08-Oct-2013
3
09-Oct-2013
4
11-Oct-2013
6
18-Oct-2013
6
21-Oct-2013
2
23-Oct-2013
4
I am looking for a query that will group the above data based on the day_identifier column data into the following format:
01-Oct-2013 11-Oct-2013 1346
18-Oct-2013 23-Oct-2013 246
The above data if expanded i.e.
all dates between 01-Oct-2013 and 11-Oct-2013 and having day of week value in 1,3,4,6
and
all dates between 18-Oct-2013 and 23-Oct-2013 and having day of week value in 2,4,6
will give me the above table's resultset.
Please help me in resolving the issue.
Thanks.

Answer 1

with
groups as
(select 'one' grp,
        to_date('01-Oct-2013','dd-Mon-yyyy') low_date,
        to_date('06-Oct-2013','dd-Mon-yyyy') high_date,
        '3,5,7' day_identifiers from dual union all
select 'two',to_date('10-Oct-2013','dd-Mon-yyyy'),to_date('16-Oct-2013','dd-Mon-yyyy'),'1,2' from dual union all
select 'six',to_date('20-Oct-2013','dd-Mon-yyyy'),to_date('26-Oct-2013','dd-Mon-yyyy'),'4,5,6' from dual
dates as
(select trunc(sysdate,'mm') + level - 1 the_date,to_char(trunc(sysdate,'mm') - level - 1,'d') day_identifier
   from dual
connect by level <= to_number(to_char(last_day(sysdate),'dd'))
select d.the_date,d.day_identifier,g.grp,g.low_date,g.high_date,g.day_identifiers
  from dates d,
       groups g
where d.the_date between g.low_date(+) and g.high_date(+)
   and instr(','||g.day_identifiers(+)||',',','||d.day_identifier||',') > 0
THE_DATE
DAY_IDENTIFIER
GRP
LOW_DATE
HIGH_DATE
DAY_IDENTIFIERS
10/01/2013
1
10/02/2013
7
one
10/01/2013
10/06/2013
3,5,7
10/03/2013
6
10/04/2013
5
one
10/01/2013
10/06/2013
3,5,7
10/05/2013
4
10/06/2013
3
one
10/01/2013
10/06/2013
3,5,7
10/07/2013
2
10/08/2013
1
10/09/2013
7
10/10/2013
6
10/11/2013
5
10/12/2013
4
10/13/2013
3
10/14/2013
2
two
10/10/2013
10/16/2013
1,2
10/15/2013
1
two
10/10/2013
10/16/2013
1,2
10/16/2013
7
10/17/2013
6
10/18/2013
5
10/19/2013
4
10/20/2013
3
10/21/2013
2
10/22/2013
1
10/23/2013
7
10/24/2013
6
six
10/20/2013
10/26/2013
4,5,6
10/25/2013
5
six
10/20/2013
10/26/2013
4,5,6
10/26/2013
4
six
10/20/2013
10/26/2013
4,5,6
10/27/2013
3
10/28/2013
2
10/29/2013
1
10/30/2013
7
10/31/2013
6
Regards
Etbin