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

# Query 2 should not include results from Query 1

## We have a Users table with over 3 million user records in it (like a data warehouse). The requirement is to execute two queries on the Users table, where the return of the second query should not have any users that were returned in the first query.

We have a Users table with over 3 million user records in it (like a data warehouse). The requirement is to execute...

two queries on the Users table, where the return of the second query should not have any users that were returned in the first query.

For example, consider a sweepstake user list, where you want to send flyers to people, notifying them about prizes, but do not want to send two flyers to the same person, even if he fulfills the selection criteria for both sweepstakes.

So --

Query 1 has conditions which state: All Users from New York, with age=25 (independently run, returns 500,000 users)

Query 2 has conditions, which state: All Users of age=25 (independently run, returns 700,000 users)

Expected Output:

Query 1 should return 500,000

Query 2 should return 700,000 MINUS those users that were already returned in Query 1, i.e., only users of age 25, but who are not from New York

Any inputs will be much appreciated!

Fascinating question. Let's assume we need separate mailout lists, one for each query, and let's assume we need separate result sets (different columns) and separate filter conditions for each query. There are three ways to write the queries. Here's one way, using NOT EXISTS:

```Query 1
select query-1-columns
from Users
where query-1-conditions
```
```Query 2
select query-2-columns
from Users as X
where query-2-conditions
and not exists
( select userid
from Users
where userid = X.userid
and query-1-conditions )```

In addition to NOT EXISTS, you can also use NOT IN or LEFT OUTER JOIN syntax. See my recent answer The difference between NOT IN and NOT EXISTS.

However, if we need just one result set, if we were doing just one mailout but still had different conditions for different sets of users, just with no overlap, then another look is warranted.

In the given example, the specific conditions were inclusive. In other words, if we need only one result set, we can run just one query with age=25 and get everybody, New York or not. It's always nice to eliminate a step that isn't necessary.

If the conditions aren't inclusive, but it's still okay to return only one result set (same columns), just not the same person twice, then a simple UNION will suffice:

```select query-columns
from Users
where query-1-conditions
union
select query-columns
from Users
where query-2-conditions```

UNION removes duplicates.

An equivalent query is:

```select query-columns
from Users
where ( query-1-conditions )
or ( query-2-conditions )```

These two queries will not necessarily perform differently, but they might.

This was last published in September 2005

## 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

• ### Apache Hadoop 3.0 goes GA, adds hooks for cloud and GPUs

Is this the post-Hadoop era? Not in the eyes of Hadoop 3.0 backers, who see the latest update to the big data framework ...

• ### Expert: For BI, you must know the data integration process

Understanding the data integration process is central to self-service BI and data architecture design, consultant Rick Sherman ...

• ### Graph technology rivals take Amazon Neptune database in stride

Amazon's Neptune database may change the status quo in the graph technology world. But it could also introduce a wider base of ...

• ### Predictive analytics projects can bolster business decisions

Blind faith in predictive models can result in flawed business decisions. Analytics teams need to manage predictive processes ...

• ### How predictive analytics techniques and processes work

Predictive analytics is no longer confined to data scientists and other highly skilled analysts. But other users need to ...

• ### Hyper engine aims to give enterprise Tableau analytics a boost

The Hyper in-memory data engine added in Tableau 10.5 could make Tableau analytics capabilities more expansive, enabling the ...

## SearchSAP

• ### SAP S/4HANA Cloud and indirect access will dominate 2018

Industry experts say SAP S/4HANA Cloud migrations, Leonardo and Cloud Platform are the technology issues for SAP in 2018; on the ...

When a Dutch energy grid provider needed to develop new business apps on top of SAP ERP, it turned to the Mendix RAD platform to ...

• ### SAP's Timo Elliott on enterprise chatbot AI technology

The SAP global innovation evangelist expects AI to affect businesses in three ways: human-computer interaction, automation of ...

## SearchSQLServer

• ### 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 ...

• ### Microsoft Cosmos DB takes Azure databases to a higher level

Azure Cosmos DB brings a new element to the database lineup of Microsoft's cloud platform, offering multiple data models and a ...

## TheServerSide.com

• ### Spring creator Rod Johnson releases API for implementing DevOps

Find out about Rod Johnson's latest project, which promises to simplify the process of implementing DevOps and streamlining the ...

• ### What Java developers need to know about TypeScript syntax

For Java developers transitioning into JavaScript frameworks, like React and Angular, this TypeScript tutorial on syntax will ...

• ### AWS Cloud9 IDE threatens Microsoft developer base

With its Cloud9 IDE, AWS challenges Microsoft where it matters most -- with the developer community, where Microsoft has ...

## SearchDataCenter

• ### Three requirements for a hybrid cloud computing deployment

As the hybrid cloud computing approach gains steam, organizations will need to pay close attention to cross-cloud connectivity ...

• ### Five debunked myths about SSD issues

Solid-state drives are mature now, and the technology has eclipsed hard disk drives with superior performance, manageability and ...

• ### Future data center trends hinge on the edge, cloud and staffing

Edge computing, colocation, cloud and IT staffing issues lead the way as industry analysts make their predictions for the future ...

## SearchContentManagement

• ### Intelligent information management the next wave for ECM

In a 2018 upgrade, M-Files allows users to search for content in multiple repositories, while also being able to automatically ...

• ### SharePoint integration and implementation best practices

Here are some expert advice and tips, as well common definitions, to help make your SharePoint integration and implementation a ...

• ### SharePoint branding capabilities get a facelift

Since Microsoft Ignite last September, SharePoint Online is getting new branding capabilities that have been on the wish lists of...

## 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