Question

this morning i involved by this query . i wasted my 2 days . but not got good solution . I have a mysql query

SELECT l.date_entered, n.date_entered, n.date_modified, n.name, n.parent_id
FROM  `notes` AS n, leads AS l
WHERE n.parent_type =  "Leads" && MONTH( l.date_entered ) =1 && YEAR( l.date_entered ) =2013 &&  
n.parent_id = l.id
ORDER BY n.date_modified ASC 

This is giving me this output:-

date_entered date_entered date_modified         name    parent_id
2013-01-07  2013-01-07    2013-01-07 20:17:44   rahul   100   
2013-01-07  2013-01-07    2013-01-07 22:27:38   rawat   101
2013-01-03  2013-01-07    2013-01-07 23:29:02   rohit   102
2013-01-03  2013-01-07    2013-01-07 23:33:55   mamta   100
2013-01-04  2013-01-08    2013-01-08 06:16:11   kiran   101
2013-01-07  2013-01-08    2013-01-08 07:10:10   ajay    100

Now, I am trying to get the date-modified difference by matching on parent_id e.g.

1. Starting with 100, search returns another 100 in 4th row. This date-modified the same day, so result = 0
2. Next search is for 101 which is found in 5th row. This date-modified is 1 day after the previous 101, so result = 1
3. Next search is for 102, which is not found, so skip it
4. Next search is for 100, but this has already been found, so skip it
5. Next search is for 101, but this has already been found, so skip it
6. Next search is for 100, but this has already been found, so skip it

my output will be such as:-

date_entered date_entered date_modified         name    parent_id   datediff
2013-01-07  2013-01-07    2013-01-07 20:17:44   rahul   100         0
2013-01-07  2013-01-07    2013-01-07 22:27:38   rawat   101         1
2013-01-03  2013-01-07    2013-01-07 23:29:02   rohit   102         not found
2013-01-03  2013-01-07    2013-01-07 23:33:55   mamta   100         skip due to previous match
2013-01-04  2013-01-08    2013-01-08 06:16:11   kiran   101         skip due to previous match 
2013-01-07  2013-01-08    2013-01-08 07:10:10   ajay    100         skip due to previous match

Answer 1

Try this :

CREATE  TABLE test as 
(SELECT l.date_entered date1, n.date_entered date2, n.date_modified mod_date, n.name name, n.parent_id parentid
FROM  `notes` AS n, leads AS l
WHERE n.parent_type =  "Leads" && MONTH( l.date_entered ) =1 && YEAR( l.date_entered ) =2013 &&  
n.parent_id = l.id);

select *,
case 
when mod_date=b.min_date and count_parent_id>1 then cast( datediff(next_date,b.min_date) as char)

when count_parent_id=1 then 'not found'
else 'skip due to previous match'
end datediff

 from  
(SELECT Date1, Date2, mod_date, name, parentid
FROM  test) as a
left join 

(select min_date,next_date, count_parent_id, q1.parentid
  from
    (SELECT min(mod_date) min_date, count(parentid) count_parent_id, parentid
    FROM  test 
    group by parentid) q1
   join
    (SELECT min(mod_date) next_date, parentid
    FROM  test 
    where  mod_date not in 
      (SELECT min(mod_date) min_date FROM  test 
      group by parentid)
    group by parentid
    )q2
   on q1.parentid=q2.parentid

) as b

on a.parentid=b.parentid
ORDER BY mod_date ASC ;

drop table test;

This works. Check SQL Fiddle