UNION and UNION ALL

UNION is an elegant bit of TSQL, allowing you to to combine (stack) result sets together into one. We've put together some examples to show you the difference between UNION and UNION ALL, and we'll look at changing the column names in the first select in order to set the column names of the final result set.

Andy Warren is a software trainer focusing on SQL Server, a member of the PASS Board of Directors, and a principal in this site - SQLShare.com.

Brian Chappell on 12/2/2010

Great snippet, very well presented. Great stuff!

Tom Hamilton on 12/2/2010

Very good - thank you

Jason Corley on 12/2/2010

Nice, I never considered Union/Union All for performance reasons.

Philip Hickey on 12/2/2010

Great video Andy - thanks

Kevin MacKay on 12/2/2010

Another great video Andy...you're right about the Sales people too :)

Rubens on 12/2/2010

Really liked the note about making a comment beside the UNION, very handy.

BABDE9F59F on 12/2/2010

This is the 1st sql video I've watched. Clear & to the point w/o fluff. Thank you!

Larry Beals on 12/2/2010

One of those little things where we have always used UNION ALL but had no idea why we did it.

Joe on 12/2/2010

Another good presentation, Andy, Kudos!

Nate on 12/2/2010

Always good to get back to the basics and remind yourself how things work.

Joyce Scarlatelli on 12/2/2010

Great! I didn't know/think about the performance between UNION and UNION ALL.

A Ranjan on 12/2/2010

Great!

Sainey M. Drammeh on 12/2/2010

Thanks for all the videos.

Jamshid Nouri on 12/2/2010

excellent

Bobby on 12/2/2010

Execellent! Thanks!

Nilesh on 12/2/2010

good video liked it

Bridget on 12/2/2010

great example

Gilles Despaties on 12/2/2010

Thanks !!! I don't use this offten. However, I am now wiser in its use.

Bruce Bealer on 12/2/2010

I did not know about the column naming. Good Tip

4A5ADA4D6E on 12/2/2010

Thanks for that information I will start adding comments too!

Derek on 12/3/2010

This was very useful--I didn't know that UNION was more CPU intensive than UNION ALL

Mat on 12/8/2010

great

Mohamed Irshad on 12/13/2010

learnt the difference between union and union all today. Thank you

Maurice Ivory on 6/20/2011

I found alot of usefull information in the Unions. An easy way to remove dups.