Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

find gap in number sequence

Posted on 2008-10-13
7
Medium Priority
?
929 Views
Last Modified: 2012-05-05
hello
for ex you have rows in a table and a columns value is:
1
2
3
5
6
you see how 4 is missing
I'm looking for a quick method to find just the first lowest missing number or gap

actually - lets say 1 is missing and there are other rows in the table
then 1 is the first gap
so I'm in need of that also

thanks
0
Comment
Question by:dgrafx
[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
  • 2
7 Comments
 
LVL 5

Accepted Solution

by:
adlink_la earned 1000 total points
ID: 22707406
You need to outer join your table to a table (or inline query) that has all of the numbers in it.  Then look for any records in your table that have nulls.
0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22707418
I would agree with adlink_la, if you don't already have a numbers table in your database I saw a good method of creating one from Brandon using common table expression. If I find I will post.
0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22707464
Check out the vw_nums code in this following post by BrandonGalderisi:
http:Q_23786715.html#a22639391
0
 [eBook] Windows Nano Server

Download this FREE eBook and learn all you need to get started with Windows Nano Server, including deployment options, remote management
and troubleshooting tips and tricks

 
LVL 5

Expert Comment

by:adlink_la
ID: 22707472
Yup.  That is a very cool little bit of code.  One thing though, you probably don't need 4 billion records.  That table might be a little large. =B
0
 
LVL 60

Assisted Solution

by:Kevin Cross
Kevin Cross earned 1000 total points
ID: 22707477
Combine that with what adlink_la is saying and you get solution like this:
SELECT MIN(n)
FROM vw_Nums v LEFT JOIN TableName t
ON v.n = t.NumberColumn
WHERE t.NumberColumn IS NULL

Open in new window

0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22707478
True!! :)
0
 
LVL 39

Expert Comment

by:BrandonGalderisi
ID: 22707705
The other thing you could do (if you are looking for gaps) is limit n to being < max.


SELECT MIN(n)
FROM vw_Nums v LEFT JOIN TableName t
ON v.n = t.NumberColumn
WHERE t.NumberColumn IS NULL
and n < (select max(t.numbercolumn) from tablename)


adlink_la "that table might be a little large"
the great thing is that it's not a table.
0

Featured Post

How to Use the Help Bell

Need to boost the visibility of your question for solutions? Use the Experts Exchange Help Bell to confirm priority levels and contact subject-matter experts for question attention.  Check out this how-to article for more information.

Question has a verified solution.

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

So every once in a while at work I am asked to export data from one table and insert it into another on a different server.  I hate doing this.  There's so many different tables and data types.  Some column data needs quoted and some doesn't.  What …
Data architecture is an important aspect in Software as a Service (SaaS) delivery model. This article is a study on the database of a single-tenant application that could be extended to support multiple tenants. The application is web-based develope…
Visualize your data even better in Access queries. Given a date and a value, this lesson shows how to compare that value with the previous value, calculate the difference, and display a circle if the value is the same, an up triangle if it increased…
We’ve all felt that sense of false security before—locking down external access to a database or component and feeling like we’ve done all we need to do to secure company data. But that feeling is fleeting. Attacks these days can happen in many w…

704 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