Solved

Difference between dates stored in Same column

Posted on 2009-05-10
7
1,069 Views
Last Modified: 2013-12-19
Hi Experts
I am actually stuck with a logic problem on a SQL query in Oracle.  
I need the difference between two dates (that are in date datatypes) that are in same column.
I tried using the ROW_NUMBER () OVER (PARTITION BY) concept but its yielding incorrect values at some places. The "Days in each status" output column is what I am looking for.  The status id is the column which has few set of statuses which get repeated for each unique person.

STATUS_CHANGE_DATE      status_id      Days in each status
            
4/9/2009 6:51      220      0 (there is no value above it so it should be 0)
4/6/2009 7:57      114      4 (diff between the 4/9 and 4/6 incl both the days)
4/6/2009 7:56      6      1 (diff between 4/6 =0 but should consider it as1)
4/6/2009 7:56      5      1
3/30/2009 14:30      111      8 (diff between 4/6 and t3/30)
3/26/2009 9:04      208      5 (diff between 3/30 and 3/26)
3/25/2009 16:17      49      2 (diff between 3/26 and 3/25)

Thanks
0
Comment
Question by:gvsbnarayana
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 3
7 Comments
 
LVL 25

Expert Comment

by:lwadwell
ID: 24351337
Hi gvsbnarayana,

The LAG() function would be better than the ROW_NUMBER() for this I think.  What is your PARTITION BY column(s)?  The LAG() function allows you to look back 'n' rows (the other one is LEAD() which allows you to look forward 'n' rows).  You could do something like

SELECT status_change_date, LAG(status_change_date,1,null) OVER(partition by some_column ORDER BY status_change_date) as prev_date
FROM ...

lwadwell
0
 
LVL 8

Author Comment

by:gvsbnarayana
ID: 24351366
My partition column is the status_id as per the above example I provided. I tried using the lag but no luck.
0
 
LVL 25

Expert Comment

by:lwadwell
ID: 24351373
lwadwell,

please show me your SQL.

lwadwell
0
Creating Instructional Tutorials  

For Any Use & On Any Platform

Contextual Guidance at the moment of need helps your employees/users adopt software o& achieve even the most complex tasks instantly. Boost knowledge retention, software adoption & employee engagement with easy solution.

 
LVL 8

Author Comment

by:gvsbnarayana
ID: 24351410
SELECT   (SELECT user_status
            FROM apps.per_assignment_status_types
           WHERE assignment_status_type_id =
                                           a.assignment_status_type_id)
                                                                       status,
         (a.status_change_date - b.status_change_date) AS days,        
         a.arowno,
         b.browno
    FROM (SELECT assignment_status_id, status_change_date, assignment_id,
                 assignment_status_type_id,
                 ROW_NUMBER () OVER (PARTITION BY assignment_status_type_id ORDER BY status_change_date)
                                                                       arowno
            FROM apps.irc_assignment_statuses) a,
         (SELECT assignment_status_id, status_change_date, assignment_id,
                 assignment_status_type_id,
                 ROW_NUMBER () OVER (PARTITION BY assignment_status_type_id ORDER BY status_change_date)
                                                                       browno
            FROM apps.irc_assignment_statuses) b
   WHERE a.assignment_status_type_id = b.assignment_status_type_id
     AND a.arowno - 1 = b.browno
     AND b.assignment_id = 649650
     order by a.status_change_date
0
 
LVL 25

Accepted Solution

by:
lwadwell earned 125 total points
ID: 24351475
gvsbnarayana,

Try this simple SQL first ...

BTW.  Are you sure the partitioning key is assignment_status_type_id?  These values must be the same across the multiple rows to form a partion.  Your examples in the original question had the values as different for each row.

lwadwell

SELECT assignment_status_id, 
       assignment_id,
       assignment_status_type_id,
       status_change_date, 
       LAG (status_change_date,1,null) OVER (PARTITION BY assignment_id ORDER BY status_change_date) prev_date
  FROM apps.irc_assignment_statuses
 WHERE assignment_id = 649650
 ORDER BY assignment_status_id, 
       status_change_date

Open in new window

0
 
LVL 8

Author Comment

by:gvsbnarayana
ID: 24351527
The Assignment Status Type id gets repeated to each Assignment id. The Assignment Status table holds the lookup values for the statuses table. So, per defintion, to form a partition I considered the  assignment status type_id as the partition key. I think that was the mistake I did.

But as per the above query I got the values for the prev value as you considered the assignment id itself and I made my modifications accordingly.

Awesome...
Thanks for the idea.  
0
 
LVL 8

Author Closing Comment

by:gvsbnarayana
ID: 31580018
Thanks for showing me the right direction
0

Featured Post

Online Training Solution

Drastically shorten your training time with WalkMe's advanced online training solution that Guides your trainees to action. Forget about retraining and skyrocket knowledge retention rates.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Note: this article covers simple compression. Oracle introduced in version 11g release 2 a new feature called Advanced Compression which is not covered here. General principle of Oracle compression Oracle compression is a way of reducing the d…
Cursors in Oracle: A cursor is used to process individual rows returned by database system for a query. In oracle every SQL statement executed by the oracle server has a private area. This area contains information about the SQL statement and the…
This video shows syntax for various backup options while discussing how the different basic backup types work.  It explains how to take full backups, incremental level 0 backups, incremental level 1 backups in both differential and cumulative mode a…
This video shows how to copy an entire tablespace from one database to another database using Transportable Tablespace functionality.
Suggested Courses

632 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question