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

# Calculating quartiles

Further to my question on percentiles, how could I return a table containing the lower and upper quartile of a...

particular variable?

This is similar to the question about percentiles, which I responded to at http://searchdatabase.techtarget.com/ateQuestionNResponse/0,289625,sid13_cid450343_tax289340,00.html. I'll use the same table and data to illustrate how to calculate quartiles. Here's the DDL:

```create table ExamResults
( Student varchar(15),
Score numeric(3)
);

insert into ExamResults values ('Lenny',94);
insert into ExamResults values ('Ralph',93);
insert into ExamResults values ('Joe',91);
insert into ExamResults values ('Mary',80);
insert into ExamResults values ('Frank',89);
insert into ExamResults values ('Susan',89);
insert into ExamResults values ('Bill',74);
insert into ExamResults values ('Ben',99);
insert into ExamResults values ('Fred',66);
insert into ExamResults values ('George',100);
insert into ExamResults values ('Walter',90);
insert into ExamResults values ('Betty',89);
insert into ExamResults values ('Heather',83);
insert into ExamResults values ('Richard',91);
```
From here, we can calculate the quotient of two scalar subqueries -- one to determine how many scored at or below a particular row, and another to determine how many rows exist in the set -- to determine where a particular row falls in the ranking. Multiplying that quotient by four and taking the ceiling of the result gives us our quartile.
```select a.*, ceiling( 4.0 *
( select count(*)
from ExamResults
where Score <= a.Score ) /
( select count(*) cnt
from ExamResults )
) quartile
from ExamResults a;
```
Here are the query results:
```STUDENT         SCORE QUARTILE
--------------- ----- --------
Lenny              94        4
Ralph              93        4
Joe                91        3
Mary               80        1
Frank              89        2
Susan              89        2
Bill               74        1
Ben                99        4
Fred               66        1
George            100        4
Walter             90        3
Betty              89        2
Heather            83        2
Richard            91        3
```

• 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 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.

This was last published in March 2002

## Content

Find more PRO+ content and other member only offers, here.

#### 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

In big data news, we find Google TPUs, or Tensor Processing Units, offered as a cloud service, while LinkedIn is open sourcing a ...

• ### Hyperledger Fabric offers path to enterprise blockchain future

Blockchain arose from bitcoin, but it's looking to find a place in the enterprise. Frameworks like Hyperledger Fabric could ...

• ### MongoDB 4.0 takes ACID transactions to multi-document level

MongoDB is taking a deeper step into SQL-style processing waters with a 4.0 update that brings increased support for ...

• ### Tableau vs. Qlik Sense: Pros and cons of the rival analytics tools

Products from the two top data visualization vendors are starting to resemble each other as the need for strong visualizations ...

• ### AI functionality limited today but could be a game-changer

Limited AI capabilities could soon give way to technology that is truly transformative for enterprises, surpassing the overhyped ...

## SearchSAP

SAP paid \$2.4 billion to acquire lead-to-money vendor CallidusCloud, and analysts agree that the significant price may be worth ...

• ### SAP's Barry Padgett on future of SAP Ariba Network

In this Q&A, new SAP Ariba President Barry Padgett discusses the future of procurement and the experience he will bring to Ariba ...

• ### Avoiding SAP indirect access woes requires good faith

Some customers are concerned that SAP will hit them for indirect access licensing fees, but they can avoid trouble if they act in...

## SearchSQLServer

SQL Operations Studio simplifies routine administration of SQL Server and Azure SQL databases, making database development and ...

• ### Meltdown and Spectre fixes eyed for SQL Server performance issues

Microsoft has responded to the Spectre and Meltdown chip vulnerabilities with patches and other fixes. But IT teams need to sort ...

• ### Five SQL Server maintenance steps you should take -- ASAP

Putting off SQL Server administration tasks can lead to database problems. Enact these often-neglected maintenance items to help ...

## TheServerSide.com

• ### IBM hones in on AI talent at developer confab

IBM and others target developers interested in building artificial intelligence applications, as the number of skilled AI ...

• ### How DevOps concepts eluted from cloud computing and service platforms

The popularity of DevOps can be traced back to the emergence of cloud computing. As programmers began scripting their ...

• ### Pluralsight IQ, Stack Overflow boost developer street cred

Tying the Pluralsight IQ skills test to the Stack Overflow Developer Story helps developers measure their technical skills and ...

## SearchDataCenter

• ### IBM Power9 servers seek market inroads to AI, cloud

IBM follows up its first Power9 server with a raft of systems designed to appeal to a wider array of markets -- most notably, AI ...

• ### Evaluate read-intensive and write-intensive SSD use cases

Consider write wear, performance and other factors when choosing between read-intensive, write-intensive and mixed-use ...

• ### Some hyper-converged infrastructure use cases pose pitfalls

Hyper-converged infrastructure adoption is skyrocketing, but that doesn't mean that the technology is the best choice for every ...

## SearchContentManagement

• ### Content management in the cloud a main theme in 2018

The future of content management resides in the cloud and with AI, as several 2018 conferences will assure you.

• ### Six things to know about today's SharePoint implementations

As companies migrate their on-premises Microsoft SharePoint sites to the cloud, here are some things they should know about the ...

• ### Upgrades for the SharePoint Online portal

As more organizations migrate SharePoint sites to the cloud, Microsoft has increased at-a-glance dashboard data and analytics to ...

## SearchHRSoftware

• ### Worksite health services providers on the rise

Employers are turning to workplace health vendors to provide on-site healthcare services to workers to reduce healthcare costs ...

• ### Federal HR applications need a makeover, Trump administration says

U.S. government HR systems are heavily customized and out-of-date. They can't share data effectively, crimping the use of people ...

• ### AI-enabled recruitment management systems seek out bias

Software for recruiters is seen as a tool in identifying hiring bias and improving diversity. The goal is to improve ...

Close