Solved

"Left Join" versus "Outer Join" in MySQL

Posted on 2007-11-16
4
4,171 Views
Last Modified: 2008-02-01
Someone asked me what is the difference between a "Left Join" and an "Outer Join" in MySQL.

My understanding is that they are the same.

Essentially there are three types of join: Left Outer, Right Outer, and Inner. All the others are just names for these.

Is this correct?
0
Comment
Question by:sypder
  • 2
  • 2
4 Comments
 
LVL 142

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 20301772
outer join, per se, does not exist. you have to specify LEFT / RIGHT OUTER JOIN.

LEFT JOIN / LEFT OUTER JOIN  are the same.
RIGHT JOIN / RIGHT OUTER JOIN are the same.

please see this page for explanations about the different JOIN s:
http://en.wikipedia.org/wiki/Join_(SQL)
0
 
LVL 3

Author Comment

by:sypder
ID: 20302032
Exactly, this is my understanding.

So what does the question "explain the difference between LEFT JOIN and OUTER JOIN" mean. Since like you said there is no OUTER JOIN and a LEFT JOIN is a LEFT OUTER JOIN.

Unless they meant to write INNER JOIN or it is a trick question.
0
 
LVL 142

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 500 total points
ID: 20302088
if you study the following mysql document, you will see confirmed that the OUTER keyword is optional, and cannot stand alone:
http://dev.mysql.com/doc/refman/5.0/en/join.html

so, either indeed this is a typo, or a trick question...
0
 
LVL 3

Author Comment

by:sypder
ID: 20302098
Thanks for confirming that. I did read that document.

It was in a job description I was applying for and it listed that knowing the difference was a key skill. So I figured I should be sure I am right before I head in.

Thanks.
0

Featured Post

What is SQL Server and how does it work?

The purpose of this paper is to provide you background on SQL Server. It’s your self-study guide for learning fundamentals. It includes both the history of SQL and its technical basics. Concepts and definitions will form the solid foundation of your future DBA expertise.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction In this article, I will by showing a nice little trick for MySQL similar to that of my previous EE Article for SQLite (http://www.sqlite.org/), A SQLite Tidbit: Quick Numbers Table Generation (http://www.experts-exchange.com/A_3570.htm…
Popularity Can Be Measured Sometimes we deal with questions of popularity, and we need a way to collect opinions from our clients.  This article shows a simple teaching example of how we might elect a favorite color by letting our clients vote for …
This Micro Tutorial hows how you can integrate  Mac OSX to a Windows Active Directory Domain. Apple has made it easy to allow users to bind their macs to a windows domain with relative ease. The following video show how to bind OSX Mavericks to …
Windows 10 is mostly good. However the one thing that annoys me is how many clicks you have to do to dial a VPN connection. You have to go to settings from the start menu, (2 clicks), Network and Internet (1 click), Click VPN (another click) then fi…

776 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question