How to find out the names which have overlapping times

Question

Hello:
I've a table which contains some names and their calling time period. I need to find out which of those names have overlapping time period.
Name|StartTime|EndTime
A|26/3/2011 12:33:16 PM|26/3/2011 12:40:10 PM
A|26/3/2011 12:41:28 PM|26/3/2011 12:43:19 PM
A|26/3/2011 12:42:28 PM|26/3/2011 12:47:50 PM
B|26/3/2011 10:22:28 PM|26/3/2011 10:50:10 PM
B|26/3/2011 10:49:28 PM|26/3/2011 10:53:50 PM
B|26/3/2011 10:50:28 PM|26/3/2011 10:59:50 PM
B|26/3/2011 10:59:58 PM|26/3/2011 11:10:50 PM
C|26/3/2011 11:05:58 PM|26/3/2011 11:10:50 PM
C|26/3/2011 11:40:58 PM|26/3/2011 11:50:50 PM
I need those names which have multiple calls and one call starts before the end of another call. If anyone have four calls and two of those overlapped (A has two overlapping and B has three overlapping), that name should also come into my list like below:
Name|Overlapping_Count
A|1
B|2
Can anyone help me please?
Thanks/Razin

Answer 1

Thans for pointing out the error in my post. It seems, being rather busy in this period, I'm starting to wear out as I missed the fact the overlaps would be returned twice. :(
I had in mind a more general case where as single row overlaps with more than one other row.
The OP's data contained one to one overlaps only and it seems no generalized approach was needed.
with
the_data as
(select 'A' name,to_date('26/03/2011 12:33:16','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 12:40:10','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'A' name,to_date('26/03/2011 12:41:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 12:43:19','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'A' name,to_date('26/03/2011 12:42:20','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 12:42:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'A' name,to_date('26/03/2011 12:42:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 12:47:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'B' name,to_date('26/03/2011 10:22:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 10:50:10','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'B' name,to_date('26/03/2011 10:49:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 10:53:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'B' name,to_date('26/03/2011 10:50:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 10:59:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'B' name,to_date('26/03/2011 10:59:58','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 11:10:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'C' name,to_date('26/03/2011 11:05:58','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 11:10:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'C' name,to_date('26/03/2011 11:40:58','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 11:50:50','dd/mm/yyyy hh24:mi:ss') end_time from dual
select name,count(distinct overlap) overlapping_count
  from (select x.name,to_char(greatest(x.start_time,y.start_time),'yyyymmddhh24miss')||'|'||to_char(least(x.end_time,y.end_time),'yyyymmddhh24miss') overlap
          from the_data x,the_data y
         where x.name = y.name
           and greatest(x.start_time,y.start_time) < least(x.end_time,y.end_time)
           and x.start_time != y.start_time
           and x.end_time != y.end_time
group by name
order by name
with
the_data as
(select 'A' name,to_date('26/03/2011 12:33:16','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 12:40:10','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'A' name,to_date('26/03/2011 12:41:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 12:43:19','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'A' name,to_date('26/03/2011 12:42:20','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 12:42:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'A' name,to_date('26/03/2011 12:42:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 12:47:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'B' name,to_date('26/03/2011 10:22:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 10:50:10','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'B' name,to_date('26/03/2011 10:49:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 10:53:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'B' name,to_date('26/03/2011 10:50:28','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 10:59:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'B' name,to_date('26/03/2011 10:59:58','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 11:10:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'C' name,to_date('26/03/2011 11:05:58','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 11:10:50','dd/mm/yyyy hh24:mi:ss') end_time from dual union all
select 'C' name,to_date('26/03/2011 11:40:58','dd/mm/yyyy hh24:mi:ss') start_time,to_date('26/03/2011 11:50:50','dd/mm/yyyy hh24:mi:ss') end_time from dual
t as
(select name,
        case when max(end_time) over(partition by name order by start_time,end_time rows between unbounded preceding and 1 preceding) > start_time
             then 0
             else 1
        end start_of_group
  from  the_data
select  name,
        count(*) overlapping_count
  from  t
where start_of_group = 0
group by name
order by nameRegards
Etbin