Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

PHP MySQL Not Equal Comparison between Two Tables

Posted on 2007-11-16
7
Medium Priority
?
2,922 Views
Last Modified: 2010-04-21
I have two tables.  MySQL version 4.1.22-standard -  PHP 5.2.4.  

I'm trying to get the data from the Review Table that do not have entries in the Comment Table.  

Here's what I have..

First Table   Review - Fields ->  (item_id / date / user_id)  

Second Table Comments - Fields -> (comm_id, item_id, user_id,date)

Code Below.. Thanks..
SELECT Review.item_id, Review.date, Review.user_id, Comments.item_id
FROM Review, Comments
WHERE Review.item_id <> Comments.item_id

Open in new window

0
Comment
Question by:usiff
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 2
7 Comments
 
LVL 48

Accepted Solution

by:
hernst42 earned 2000 total points
ID: 20296803
You can try the SQL below
SELECT Review.item_id, Review.date, Review.user_id
FROM Review LEFT OUTER JOIN Comments on (Review.item_id = Comments.item_id)
WHERE Comments.item_id IS NULL

Open in new window

0
 
LVL 7

Expert Comment

by:dansoto
ID: 20297975

SELECT Review.item_id, Review.date, Review.user_id, Comments.item_id
FROM Review
WHERE Review.item_id NOT IN 
(SELECT Comments.item_id from Comments); 

Open in new window

0
 

Author Comment

by:usiff
ID: 20299640
Hello hernst42:

Here is another quick issue..

When I add this code below is doesn't work...
WHERE Comments.item_id IS NULL AND Review.user_id = $_SESSION['user_login_id']

But this will work?
WHERE Comments.item_id IS NULL AND Review.user_id = '444'

What the heck I'm I missing?

Thanks

usiff
0
Ransomware-A Revenue Bonanza for Service Providers

Ransomware – malware that gets on your customers’ computers, encrypts their data, and extorts a hefty ransom for the decryption keys – is a surging new threat.  The purpose of this eBook is to educate the reader about ransomware attacks.

 
LVL 48

Expert Comment

by:hernst42
ID: 20299795
maybe $_SESSION['user_login_id'] is empty and does not contain anything. What do ypu get when you print out var_dump($_SESSION['user_login_id']) before you create the SQL?
0
 

Author Comment

by:usiff
ID: 20300288
Hello hernst42,

It's printing our string(1) "444"

It's crazy..
0
 

Author Comment

by:usiff
ID: 20300316
It's working now..  Wow...  I was going crazy!!  

I love typosss

Thanks again!

0
 

Author Closing Comment

by:usiff
ID: 31409512
Thanks!
0

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

This article discusses how to implement server side field validation and display customized error messages to the client.
In this article, I’ll talk about multi-threaded slave statistics printed in MySQL error log file.
This tutorial will teach you the core code needed to finalize the addition of a watermark to your image. The viewer will use a small PHP class to learn and create a watermark.
In this video, Percona Solution Engineer Dimitri Vanoverbeke discusses why you want to use at least three nodes in a database cluster. To discuss how Percona Consulting can help with your design and architecture needs for your database and infras…

722 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