Question

I have a table has data similar to below

  Emp  Date        Code     
  ---  --------    ---- 
  E1  11/1/2012    W 
  E1  11/1/2012    V   
  E2  11/1/2012    W   
  E1  11/2/2012    W
  E1  11/3/2012    W
  E1  11/4/2012    W
  E1  11/5/2012    W

I want to get list of employees between a date range(say for the last 3 months) who worked for code W conescutively for 5 days with the date range in the output. Each employee can have multiple records for a single day with different codes.

Expected Output is

Emp   Date-Range 
---   ----------
 E1   11/1 -11/5

Below is what I tried but I didn’t come close at all to the output I seek

 SELECT distinct user, MIN(date) startdate, MAX(date) enddate
FROM (SELECT user, date, (TRUNC(date) - ROWNUM) tmpcol
      FROM (SELECT user, date
              FROM tablename
             where date between to_date('10/01/2012','mm/dd/yyyy') and to_date('10/03/2012','mm/dd/yyyy')
             ORDER BY user, date) ot) t
 GROUP BY user, tmpcol
 ORDER BY user, startdate;

If Emp E1 has worked for 10 consecutive days, he should be listed twice in the output with both date ranges. If E1 has worked for 9 days consecutively(11/1 to 11/9), he should be listed only once with the date range 11/1 to 11/9.

I have already seen questions which are similar but none of them exactly worked out for me. My database is Oracle 10G and no PL/SQL.

Answer 1

I’m not sure I understood everything correctly, but something like this might get you started:

select emp, 
       sum(diff) as days,
       to_char(min(workdate), 'yyyy-mm-dd') as work_start,
       to_char(max(workdate), 'yyyy-mm-dd') as work_end
from (       
  select *
  from (
    select emp, 
           workdate, 
           code, 
           nvl(workdate - lag(workdate) over (partition by emp, code order by workdate),1) as diff
    from tablename
    where code = 'W'
     and workdate between ...
  ) t1
  where diff = 1 -- only consecutive rows
) t2
group by emp
having sum(diff) = 5

SQLFiddle: http://sqlfiddle.com/#!4/ad7ae/3

Note that I used workdate instead of the date as it is a bad idea to use a reserved word as a column name.