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

Validating a pair of columns with range tests

I have two fields "zipfrom" and "zipto" in one table. I want to compare another two fields (user-entered) with these fields to validate that the user-entered zip range is unique in the table. For example,

```Table
zipfrom  zipto
51000    52000```

If the user enters 51150-51175 then we should return error that this range is already entered.

In the example you've given, the codes 51150-51175 represent a range of numbers that lie completely within the range 51000-52000. I shall assume that you also want to issue an error if the user-entered range overlaps an existing range at either end. These three conditions are illustrated below, where X------X is an existing range already in the database, and A----A, B----B, and C----C are ranges for which you want to issue an error --

```     X----------X
A----A
B-------B
C------C```

You can check all three of these conditions by noting that at least one of the endpoints of a "bad" user-entered range is within the existing range --

```create table zipranges
( zipfrom char(5)
, zipto char(5)
, constraint rangecheck1
check ( not exists
( select * from zipranges XX
where zipfrom between XX.zipfrom and XX.zipto
or zipto   between XX.zipfrom and XX.zipto )
)
);```

However, not every database is going to let you declare a constraint that way, with a subquery. At worst you would have to write some programming logic to perform the NOT EXISTS test before deciding to insert. Another problem with this type of check constraint, as pointed out by Joe Celko on page 160 of SQL Puzzles & Answers (ISBN 1-55860-453-7), is that you will have trouble inserting an initial row into an empty table.

There's one more problem, too. What if the user enters a range that spans an existing range?

```     X----------X
A---------------A```

This, too, can be covered by a check constraint --

```  , constraint rangecheck2
check ( not exists
( select * from zipranges YY
where zipfrom < YY.zipfrom
and zipto   > YY.zipto )
)```

For More Information

• What do you think about this answer? E-mail the edtiors at editor@searchDatabase.com with your feedback.
• The Best SQL Web Links: tips, tutorials, scripts, and more.
• Have an SQL tip to offer your fellow DBAs and developers? The best tips submitted will receive a cool prize. Submit your tip today!
• Ask your technical SQL questions -- or help out your peers by answering them -- in our live discussion forums.
• Ask the Experts yourself: Our SQL, database design, Oracle, SQL Server, DB2, metadata, object-oriented and data warehousing gurus are waiting to answer your toughest questions.

Have a question for an expert?

Please add a title for your question

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

• Dremio Data Lake Engine 4.0 accelerates query performance

Dremio issues a new platform update, defining itself as data lake engine technology that looks to help users connect and query ...

• Weighing the use of third-party database administration tools

Database expert Chris Foot details the key reasons why DBAs should consider using third-party database administration to fill ...

• InfluxDB Cloud 2.0 expands open source time series database

While the core open source InfluxDB 2.0 project is still in alpha, InfluxData has advanced its cloud service to support new ...

SearchBusinessAnalytics

• Qlik exec discusses AI and its role in the future of BI

The next major trend in business intelligence will be the increasing impact of augmented intelligence and machine learning, ...

• SAP BI platform stays strong due to cloud-based architecture

A cloud-native BI platform along with domain-specific applications that can be embedded to serve the needs of various industries ...

• Tableau 2019.3 highlighted by enhanced AI, new data catalog

Tableau released its third-quarter update Wednesday, featuring Explain Data, an enhanced augmented intelligence tool, and Tableau...

SearchSAP

• Navy sails SAP ERP systems to AWS GovCloud

The Navy consolidated 26 various ERP systems onto SAP HANA on the AWS GovCloud, leading to data reduction, lower TCO, and setting...

• SAP HANA application collects concussion data for real-time analysis

Protecht, an SAP HANA based system, enables teams in contact sports to measure and analyze data about hits though an IoT sensor ...

• S/4HANA public cloud vs. private cloud: Compare the pros, cons

In addition to SAP's on-premises and hybrid models, the vendor offers S/4HANA in public and private clouds. Here's a look at the ...

SearchSQLServer

• SQL Server database design best practices and tips for DBAs

Good database design is a must to meet processing needs in SQL Server systems. In a webinar, consultant Koen Verbeeck offered ...

• SQL Server in Azure database choices and what they offer users

SQL Server databases can be moved to the Azure cloud in several different ways. Here's what you'll get from each of the options ...

• Using a LEFT OUTER JOIN vs. RIGHT OUTER JOIN in SQL

In this book excerpt, you'll learn LEFT OUTER JOIN vs. RIGHT OUTER JOIN techniques and find various examples for creating SQL ...

TheServerSide.com

• Microsoft vs. IBM: A major shift in Java support

Once an afterthought in the Java community, Microsoft has seemingly overtaken IBM as the preeminent advocate among developers at ...

• Guide to practicing cloud-native development

In this guide, learn about cloud-native development -- what it is, how vendors try to exploit it and how to bring it to life with...

• Eclipse launches Che 7 IDE for Kubernetes development

The Eclipse Foundation has introduced Eclipse Che 7, a new version of the Eclipse Che cloud-based integrated development ...

SearchDataCenter

• New Dell EPYC servers embrace AMD Rome chips

Dell EMC goes from Naples to Rome with a new line of EPYC servers, including Ready Solutions for high-performance computing and ...

• Can next-gen SIEM help cybersecurity initiatives?

More organizations are using SIEM, AI and cloud technology to minimize security breaches. Though despite interest, this ...

• IBM z15 mainframe secures data across multi-cloud environments

IBM unveiled the latest in its line of mainframes capable of processing 1 trillion web transactions a day. The IBM z15 ...

SearchContentManagement

• Nintex launches no-code workflow automation tool

Nintex has launched a no-code workflow automation tool, Workflow Generator, in an effort to bridge the gap between IT departments...

• Cohesion is latest Acquia acquisition

While Acquia would not provide specifics of the deal, the decision behind the acquisition of Cohesion was the chance to bring ...

• 3 things to learn before considering blockchain integration

Paul Swider, CTO at RealActivity LLC, discusses how to use blockchain technology to increase the security and usefulness of ...

SearchHRSoftware

• SuccessFactors customers to see big Qualtrics impact

SuccessFactors is rethinking its HCM suite as it works to integrate Qualtrics into its applications. But HR managers are ...

• HiQ Labs vs LinkedIn case OKs robot monitoring of employees

A U.S. Court of Appeals ruled on the LinkedIn vs HiQ lawsuit, which could help shape how services gather information on social ...

• MyPayrollHR collapse stirs allegations, questions, anger

The problems created by the closing of MyPayrollHR may take a long time to resolve. The FBI has been contacted and lawsuits are ...

Close