Q
Problem solve Get help with specific problems with your technologies, process and projects.

# Sorting substrings of different lengths numerically

I have a table which contains IP addresses, such as 192.192.192.50. I want to display the table sorted by IP address...

(which is the primary key, a string), but unfortunately 192.192.192.19 will appear before 192.192.192.2!

The general solution to sorting strings of numbers of different lengths is to concatenate each of them onto the right end of a string of enough zeroes, and then take a substring of the desired length from the right.

For example, if we concatenate '123', '45', and '6' onto '00', we get '00123', '0045', and '006'. If we then take the rightmost 3 characters, we get '123', '045', and '006'. This is the strategy we shall apply to the IP numbers.

IP numbers contain four groups of digits, each of which can be between 1 and 3 digits long. We need a way to search a string or substring looking for the first occurrence of a specific character, in this case a period. We also need to pull substrings out, pad them with zeroes where necessary, and take the rightmost three characters to sort on. Each of the four groups can vary in size, so this will get tricky.

Standard SQL provides the SUBSTRING and POSITION functions, but these aren't supported by every database. For the following examples, I'll use Microsoft Access syntax, and the MID, INSTR, and RIGHT functions -- MID and RIGHT are special versions of SUBSTRING, and INSTR performs the POSITION function.

Let's get the first group of digits. We need a substring, starting at the very first character on the left, and going up to the last character before the first period --

```MID( IPno
, 1
, INSTR(IPno,'.')-1
)```

INSTR(IPno,'.') returns the position of the first period, which will be 2, 3, or 4, depending on whether the first group of digits is 1, 2, or 3 digits long. The MID function starts at the first character of IPno, and goes for a length equal to the position of the first period minus 1, i.e. up to the last character before the period.

Once we have pulled out the digits of the first group, we need to pad them on the left with zeroes and take the rightmost 3 characters --

```RIGHT( '00'
& MID( IPno
, 1
, INSTR(IPno,'.')-1
)
, 3
)```

From here on it gets messier. To pull out the second group of digits, we have to start one character to the right of the first period, search for the next period in that substring, and then pull out the second group like this --

```MID(IPno
,INSTR(IPno,'.')+1
,INSTR(MID(IPno
,INSTR(IPno,'.')+1)
,'.')-1)```

Notice that the length parameter, which determines how long a substring we're getting, is based on the position of the second period.

This response is continued.

This was last published in June 2002

#### Have a question for an expert?

Get answers from a TechTarget expert on whatever's puzzling you.

You will be able to add details on the next page.

#### Start the conversation

Send me notifications when other members comment.

## SearchDataManagement

• ### Chief data officer role: Searching for consensus

The chief data officer role is about many things -- regulations, innovation, AI and more. Consultant Randy Bean discussed the ...

• ### How graph data modeling can help evaluate database tools

Mapping data to a graph model can be challenging -- but it can also help an organization create prototypes to evaluate graph ...

• ### eHarmony hooks up with Redis NoSQL database for hot storage

The Redis key-value store finds use in a system to match would-be romantic partners on dating site eHarmony, which employs a ...

• ### Heat map view sets table for food warehouse optimization

Inspired by the vivid views of stadium heat maps, a Midwest food distributor worked with Information Builders to gain a better ...

• ### Streamlining predictive analytics in retail marketing

Online flash-sale retailer Zulily uses BigQuery and Tableau to help power its predictive analytics, which, in turn, boosts its ...

• ### Airbnb, Univision highlight best practices in BI

At the Real Business Intelligence conference, Airbnb and Univision execs presented some of the BI strategies their organizations ...

## SearchSAP

• ### On-premises, hosted most popular S/4HANA deployment options

The pure cloud -- SaaS -- version of SAP's newest ERP, S/4HANA Cloud, lacks some of the same features of the on-premises version....

• ### S/4HANA public cloud version can get lost in cloud confusion

The 'true' public cloud is the streamlined SaaS version of on-premises S/4. But private cloud options are often conflated with ...

• ### SAP S/4HANA migration: What you need to know

There's a lot to consider when contemplating a move to SAP S/4HANA, and this essential guide provides a starting point, including...

## SearchSQLServer

• ### A quick tutorial on SQL Server maintenance plans

SQL Server maintenance plans get a bad rap, but for DBAs who need a simple way to maintain databases, Microsoft's built-in tools ...

• ### Proposed Microsoft-GitHub buy confirms open source role in cloud

The looming Microsoft-GitHub pairing confirms the company's rebirth as an open source friend. Data tools on the Azure cloud are ...

• ### Common Data Service for Analytics eases Power BI integration

Integrating data into Power BI for analysis can be a challenge, but Microsoft's Common Data Service for Analytics technology is ...

## TheServerSide.com

• ### Attain Jenkins Git integration with a GitHub pull request

This Jenkins Git integration tutorial demonstrates how to create a freestyle build job that performs a Jenkins GitHub pull ...

• ### Financial firms, vendors push self-service software delivery

Self-service DevOps automation appeals to enterprises that must push out new code as they adapt to changing requirements.

• ### IT projects and software teams need to include Agile people

Not every idea deserves equal weight in a software development project, but Agile people know that garnering input from a wide ...

## SearchDataCenter

• ### Rackspace colocation program hosts users' legacy servers

Rackspace now has a managed colocation program that it hopes to upsell its customers with additional services, once their servers...

Broadcom has acquired CA Technologies in a move some believe is largely financially motivated, while others see an opportunity ...

• ### Ten Linux process management commands that simplify admin workflows

If you work in Linux, chances are you have to do some process management. Here are some commands to simplify that workflow.

## SearchContentManagement

• ### Endpoint security tool fueled OpenText's Guidance Software acquisition

Endpoint security was the primary draw for OpenText's Guidance Software acquisition. But plans to improve e-discovery and data ...

• ### Digital transformation benefits follow a not-so-fast track

Choosing among the many digital transformation strategies in the content management sphere is not easy but can pay off when ...

• ### Customers, vendors differ on digital transformation definition

Digital transformation may be the talk of the analyst sphere and the marketing domain, but people using the technology aren't ...

## SearchHRSoftware

• ### Automated recruiting solves Groupon's sourcing talent woes

Building a talent pool through effective sourcing is a major effort by Groupon. It is using a recruiting automation tool to find ...

• ### New HR tools for hourly workers, employee retention announced

This week's news roundup includes an HR tool designed just for hourly workers, a new offering from Limeade to help with talent ...

• ### Eight human capital management functions every HR department needs

Employee self-service and wellness portals are no longer enough. Now, you need a multipronged strategy that tackles the most ...

Close