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

# Summing across columns

I have an SQL database table that stores names and scores. There are multiple score columns, one for each week. If a player did not play that week, he/she is given a NULL score. If a player did play that week but did not score points, he/she is given a score of 0. The problem is finding the top ten players overall. I need to sum values across the columns, and the SUM() function appears to only sum columns. Is there any way to do this with MySQL, or any RDBMS? Thank you.

First of all, congratulations on understanding the difference between NULL and zero.

The best way to do this, of course, is to normalize your table. Create a second table, give it a primary key of playerid and weekno, with one column for the score for that week. If a player did not play a particular week, there would be no row for that player that week. This structure is better in a number of ways, not least of which is that you can then use SUM().

With your structure, there's no alternative but to do the addition across each row. Here, you have to be careful not to add in a NULL, because then the row summary will be NULL. Therefore, you have to use COALESCE.

```select playerno
, coalesce(week1,0) +
coalesce(week2,0) +
coalesce(week3,0) +
coalesce(week4,0) + ...
as playersum
from scores
group
by playerno```

This is fine, as far as it goes, but you will have even more of a headache if you have to find the average score for the games that the player did play, because then you have to count the number of scores that aren't null.

```select playerno
, coalesce(week1,0) +
coalesce(week2,0) +
coalesce(week3,0) +
coalesce(week4,0) + ...
as playersum
, case when week1 is null
then 0 else 1 end +
case when week2 is null
then 0 else 1 end +
case when week3 is null
then 0 else 1 end +
case when week4 is null
then 0 else 1 end + ...
as weeksplayed
, ( coalesce(week1,0) +
coalesce(week2,0) +
coalesce(week3,0) +
coalesce(week4,0) + ... )
/
( case when week1 is null
then 0 else 1 end +
case when week2 is null
then 0 else 1 end +
case when week3 is null
then 0 else 1 end +
case when week4 is null
then 0 else 1 end + ... )
as averagescore
from scores
where not ( week1 is null
and week2 is null
and week3 is null
and week4 is null ...)
group
by playerno```

Ewww. Anyhow, imagine you have these queries written and tucked away inside your application, all ready to roll out into production, and somebody comes along and says "Hey, let's extend the season by one more week..."

Oh, and regarding your top 10 question? See FIRST N rows, TOP N rows, LAST N rows, BOTTOM N rows... and imagine substituting the average score calculation above into the variable "foo" in some of those syntax examples.

This was last published in January 2003

## 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

• ### Connectedness is king, as Neo4j graph database ports to Spark

The Neo4j graph database emphasizes easy relationship mapping for diverse data points. Now, its related Cypher query language is ...

• ### NewSQL databases rise anew -- MemSQL, Spanner among contenders

The NewSQL database was almost hidden when Hadoop and NoSQL arose. Now, as more big data teams move toward production uses, ...

• ### Good data quality for analytics becomes an IT imperative

High-quality data is a must for analytics applications. That's driving more demand for data quality tools, but quality ...

• ### Tableau targets data preparation software with Project Maestro

As Tableau and other high-level applications look to automate more functionality, stand-alone data preparation tools have to ...

• ### AI components make tools more than the sum of their parts

AI applications, rather than being one monolithic tool, are built around a diverse collection of tools and techniques that ...

• ### At AT&T, CDO responsibilities to include all things AI

At most companies, the chief data officer role tends to focus on data governance and management issues, but at AT&T, AI is set to...

## SearchSAP

• ### Responsible sourcing can be good for business

A company's reputation and bottom line can be damaged if its suppliers engage in harmful practices. Responsible sourcing and risk...

• ### SAP TechEd 2017 focuses on next-gen development tools

At SAP TechEd 2017, SAP rolled out some new developer tools that are intended to extend the SAP platform and drive development of...

• ### SAP Analytics Cloud helps paper-maker tell a good business story

SAP Analytics Cloud software is helping paper manufacturer Pratt Industries tell the story of monthly forecasts more accurately, ...

## SearchSQLServer

• ### Microsoft technology refresh touches SQL Server, integration tooling

Microsoft is at work on a delicate technology refresh affecting database tuning and architecture, as well as data integration and...

• ### Microsoft boosts SQL Server machine learning services

Python and R are among the tools in the SQL Server machine learning toolkit. Native T-SQL scoring is also on the agenda, as ...

• ### Power BI updates drive Microsoft's latest hybrid cloud efforts

At PASS Summit 2017, Microsoft Azure's strides were measured in steps. These include Power BI updates that bring cloud reporting ...

## TheServerSide.com

• ### Can DevOps problems actually cause projects to fail?

DevOps isn't perfect. There are times when DevOps problems can overwhelm the potential benefits. So, why do some DevOps projects ...

• ### Owning the Java Platform is more of a burden or a blessing

Oracle became stewards of the Java platform as a by-product of their acquisition of Sun Microsystems. But looking back, it seems ...

• ### Migrations to Oracle's Java SE 9 platform may be delayed

Oracle did a great job getting Java SE 9 released earlier this year, but modularity and various smaller updates may not be enough...

## SearchDataCenter

• ### Data center GPU use on the rise thanks to AI, big data

GPU vendors have added new devices and cards for data center servers, as data demanding workloads infiltrated the data center and...

• ### SD-WAN benefits branch networks with simplicity, automation

Traditional branch networks haven't adapted well to new technologies. But a mature SD-WAN market can bring distributed networks ...

• ### Composable infrastructure creates new path to SDDC nirvana

Shiny new products like composable infrastructure and on-premises cloud platforms could offer a way to achieve software-defined ...

## SearchContentManagement

• ### Q&A: New CEO bets on open source future for Acquia CMS

The Acquia CMS took the Red Hat model to content management by commercializing open source Drupal. What's next? We ask co-founder...

• ### CMS analytics arms businesses with a strategic planning edge

Content analytics for CMSes mines business value from free text in data lakes, so it's time to go prospecting for gold with this ...

• ### Enterprise content management systems boost intelligence

Content analytics moves beyond the tried-and-true web analytics style of insights, adding natural language processing and images ...

## SearchFinancialApplications

• ### Finance IT case study: Reporting secrets of Derek Rose

CEO Sacha Rose says specialist reporting tools have saved the company thousands by avoiding unnecessary mistakes.

• ### WestJet turns to gamification to help its Oracle ERP users soar

WestJet's initial gamification project focuses on expense reporting.

• ### The Transformation of HR is Underway

HR is being transformed while we watch.

Close