3 way join SQL

Posted on 2008-10-27
Last Modified: 2012-05-05
I'm trying to connect 3 tables in my database: organizations, category_values and users_categories. If I change this:
where (uc.uid = '3' AND cv.catId='163')
to this:
where (uc.uid = '3')
I get all of the results I would expect. But adding the cv.catId I get 0 results (query runs with no errors). Is there something structurally wrong with my query?
$query = "select distinct o.orgId,, cv.catId
	from (organizations o join category_values cv
	on cv.orgId = o.orgId) join users_categories uc
	on uc.catId = cv.catId
	where (uc.uid = '3' AND cv.catId='163')
	order by ASC";

Open in new window

Question by:level9wizard
  • 3
  • 2
LVL 11

Author Comment

ID: 22815236
As some more info, when I print row data the catId is the same for every row result. As if it's taking it from uc.catId and not cv.catId
LVL 143

Accepted Solution

Guy Hengel [angelIII / a3] earned 500 total points
ID: 22819994
what about this:
$query = "select distinct o.orgId,, cv.catId
        from organizations o join category_values cv
        on cv.orgId = o.orgId 
        left join users_categories uc
        on uc.catId = cv.catId and uc.uid = '3' AND cv.catId='163'
        order by ASC";

Open in new window

LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 22819997
otherwise, you might not have any rows matching both criteria?!
LVL 11

Author Comment

ID: 22821413
I got the answer I was looking for thru IRC, thought i'd share...

$query = "SELECT o.orgId,, cv.catId FROM organizations o join (
SELECT DISTINCT cv2.orgId FROM users_categories uc JOIN category_values cv2 on uc.catId=cv2.catId WHERE uc.catId=200 and uc.uid=3 ) as d ON d.orgId=o.orgId
JOIN category_values cv ON d.orgId=cv.orgId
WHERE cv.catId='163'";
LVL 11

Author Closing Comment

ID: 31510383
The real solution to my problem is below, but I want to award you points for trying. Thanks!

Featured Post

Windows Server 2016: All you need to know

Learn about Hyper-V features that increase functionality and usability of Microsoft Windows Server 2016. Also, throughout this eBook, you’ll find some basic PowerShell examples that will help you leverage the scripts in your environments!

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
sql_mode 1 30
configure dependency in POM for new database 3 34
Excel - SQL export question 3 50
insert into database through form with dynamic fields. 2 37
Fore-Foreword Today (2016) Maxmind has a new approach to the distribution of its data sets.  This article may be obsolete.  Instead of using the examples here, have a look at the MaxMind API ( …
This guide whil teach how to setup live replication (database mirroring) on 2 servers for backup or other purposes. In our example situation we have this network schema (see atachment). We need to replicate EVERY executed SQL query on server 1 to…
This video shows how to quickly and easily add an email signature for all users on Exchange 2016. The resulting signature is applied on a server level by Exchange Online. The email signature template has been downloaded from: www.mail-signatures…

828 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