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

# Exactly one row? At least one row? (Part 1)

I am trying to retrieve data from one table, but I want specific data from two different columns. My example table...

is:

``` ID LOC_NUMB LOC_PREC 000000000 TIRE01 P 000000001 TIRE02 P 000000002 TIRE03 P 000000003 TIRE04 P 000000004 TIRE05 P 000000001 TIRE06 S 000000002 TIRE07 S
```

The results I am looking for:

``` ID LOC_NUMB LOC_PREC 000000001 TIRE02 P 000000002 TIRE03 P 000000001 TIRE06 S 000000002 TIRE07 S
```

I need ID with the LOC_PREC P and S.

``` SELECT item_loc.id, item_loc.loc_numb, item_loc.loc_prec FROM item_loc WHERE item_loc.id contains **** this is where I am having a problem (item_loc.loc_prec 'S and P') GROUP BY item_loc.id ORDER BY item_loc.id asc
```

Is there any way I can get the data from column ID that contains only S and P for that specific ID. I don't need AND, OR; I need both? Thank you.

To answer your question, yes, you can do it. You didn't say whether you wanted exactly one S and and P, or at least one S and one P, so I'll show you how to do it either way. Let's start with this query:

```select id , loc_numb , loc_prec from item_loc where id in ( select id from item_loc where loc_prec in ('S','P') group by id having count(*) = 2 )
```

Let's look first at the subselect. The subselect returns all S and P rows in the table. Then it groups them by ID. If a particular ID has exactly 2 rows, then it is selected, and both of its rows are included in the result set of the outer query.

But is this correct? We are assuming that there is one S and one P, but there's a "gotcha" in that logic. The subquery also chooses every ID that has two S's and no P's, or two P's and no S's. And if there's a particular ID that happens to have one S and two P's? It would not be chosen! We could fix this by using

``` having count(*) >= 2
```

But this still lets an ID with only three P's or only three S's through.

This is familiar OR behaviour, the result of "mingling" the selected rows in the IN?('S','P') condition. Let's see what happens when we split the S and P conditions into separate subselects, so that the selected rows are not mingled.

```select id , loc_numb , loc_prec from item_loc where id in ( select id from item_loc where loc_prec = 'S' group by id having count(*) = 1 ) and id in ( select id from item_loc where loc_prec = 'P' group by id having count(*) = 1 )
```

This query lists ID's which have exactly one S and one P. Use an equality condition in the HAVING clause to specify an exact number of rows.

To find one or more rows, use an inequality. For example, to find every ID with one S and at least one P, the query is:

```select id , loc_numb , loc_prec from item_loc where id in ( select id from item_loc where loc_prec = 'S' group by id having count(*) = 1 ) and id in ( select id from item_loc where loc_prec = 'P' group by id having count(*) >= 1 )
```

If you think about it for a moment, a HAVING clause that says COUNT(*)?>=?1 is redundant. It's easy to see why, if you consider how a query with a GROUP BY clause is processed. First, rows are retrieved based on WHERE conditions. Then the selected rows are assembled into groups, typically by sorting. Then the groups are processed. There will not be a group with no rows, since during selection, no rows were selected for that group. Therefore each group that comes out of row selection and goes into group processing has to have one or more rows.

This was last published in October 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

• ### Blockchain data disruption aborning, IDC analyst says

Blockchain data technology disruption may be in the offing. IDC's Stewart Bond says architecture at the core of controversial ...

• ### Potent NoSQL architecture engaged for building new applications

Behind hyperbolic terms like 'digital transformation' are innovative systems of engagement. DataStax CEO Billy Bosworth joins ...

• ### Finance data governance program gets new start, broader focus

Businesses constantly need to evolve their programs for governing data. Nationwide's finance data governance team shares how it ...

• ### Cognitive computing technologies still deliver mixed results

Cognitive computing tools have come a long way in the last couple of years, but the notion of true cognitive businesses, built ...

• ### Deloitte report reveals the power of unstructured data analytics

The analysis of unstructured data and other so-called dark data types can deliver significant business value, according to a new ...

• ### Ease of use is top priority in selecting self-service analytics tools

A lot of factors go into a choosing a strong, modern BI tool. But several users say ease of use trumped all other considerations ...

## SearchSAP

• ### Future of Ariba Network on display at SAP Ariba Live

SAP Ariba Live shows enhancements to procurement software and looks at the future of the SAP Ariba Network, including machine ...

SAP Vora has been updated to include features that make it easier to deploy and use to get insights from Hadoop big data; SAP IBP...

• ### Chatbots provide faster self-service on SAP systems

The SAP SuccessFactors partnership with collaboration software vendor Slack is just one of many efforts to make little robotic ...

## SearchSQLServer

• ### Redgate tools help bring database DevOps to Visual Studio 2017

So far, data has been left out of the DevOps discussion. But DevOps for databases could grow if tools like Redgate's bundle ...

• ### Conquer real-time operational analytics in SQL Server 2016

Analytics helps improve business operations, and SQL Server 2016 users can master it -- in real time, using operational data in a...

• ### SQL Server machine learning goes full throttle on operational data

Artificial intelligence is a hot topic in IT, and Microsoft has made strides to synchronize SQL Server with machine learning ...

## TheServerSide

• ### Does reading XML while writing JSON make me a bad person?

I'm always writing JSON code, loving its flexibility and forgiveness. But when I call an external service, I want to be reading ...

• ### Declarative Jenkins pipeline the latest new feature in DevOps tooling

Looking to get more out of your DevOps tooling? The declarative Jenkins pipeline helps take continuous integration and continuous...

• ### Amazon S3 outage a Fukushima moment for cloud computing

The Amazon S3 outage has turned into the Fukushima moment of cloud computing, as users re-evaluate the cloud's long-term ...

## SearchDataCenter

• ### Manage and optimize IBM z Systems software costs

Some mainframe users find it tough to navigate IBM's sub-capacity pricing model. Consider tools like SCRT to more efficiently ...

• ### Find the right data center cooling systems for hyper-converged

Hyper-converged infrastructure can cause new data center cooling challenges. Before implementation, determine which temperatures ...

• ### IBM's cloud dreams soar on the wings of AI, open source

Hoping to play catch-up with its web services archrivals, IBM has rolled out a raft of products and services fueled by AI and ...

## SearchContentManagement

• ### Seven features to consider when picking enterprise collaboration tools

As collaboration needs grow, more options are beginning to sprout up. Here are the features to think about when selecting the ...

• ### Microsoft Teams joins growing business chat software market

The general release of Microsoft's latest product puts Slack square in its scope, with hopes of taking a chunk from the business ...

Headless CMS can be a difficult pivot for dyed-in-the-wool legacy shops, but remixing content in this new model with RESTful APIs...

## SearchFinancialApplications

• ### Report rates e-sourcing, spend analysis and contract management tools

Gartner Magic Quadrant finds plenty of room for growth in market for cloud-based strategic sourcing application suites that can ...

• ### Benefits administration systems that use analytics liked by employers

HR tech systems are increasingly using analytics in benefits administration, including using claims data; meanwhile, APIs are ...

• ### Degreed integrates and organizes content from online learning software

Atlassian and Intel use cloud-based Degreed to integrate e-books, articles, videos and other content and recommend training for ...

Close