Solved

Adding a LIMIT on a specific column in SELECT query

Posted on 2007-12-02
3
161 Views
Last Modified: 2010-03-20
Hi All,

OK, this one is a bit of a brain buster but I'm sure you lot will be able to spot it in no time. I've been looking at it for too long and need to step back for a moment.

The following query retrieves creative's (a creative is a user) from the database on a per-group (like a category) basis from table 'creative'.

Note: $desc is an integer relating to the category (or group) we want to know about.

$sql = "SELECT DISTINCT(c.id) FROM creative c, creative_group g, group_discipline gd WHERE c.id = g.creative_id AND g.group_id = gd.id AND ( gd.id = '$disc' OR gd.map_ids = '$disc' /* new bit - select people who are in 'child' groups too */ ) AND c.visible = 1 AND c.active = 1 ORDER BY g.status, c.boxed DESC, g.display_order, c.date_updated DESC, g.pk_id DESC";

It just allows us to find out how many users are within each category.

When a user registers, they specify the categories of interest to them. These are stored in 'creative_group' in order of relevance. So the user will select their primary categories of interest first. For the purpose of the query above, I want to retrieve the same data but only for users where the $desc group whatever that may be, was in their top 3 choices.

Table creative_group looks like this:

pk_id (Primary Key and AUTO INCREMENT)
group_id
creative_id

Image the following data within creative_group

=====================================
|     pk_id     |     group_id      |     creative_id     |
=====================================
|      167      |          75           |             56           |
|      168      |          36           |             56           |
|      169      |          15           |             56           |
|      170      |          21           |             56           |
|      171      |          11           |             56           |
|      172      |          58           |             56           |
|      173      |           9            |             56           |
=====================================

This tells us that user id 56 has shown interest in 7 categories (groups) and that group_id 75 is of most interest to them, followed by 36 and then that in which they are least interested, group_id 9. What I want to do with the query I gave, is make sure it would only return the above user id 56 if $desc was either 75, 36 or 15, as they were in said user's top 3 choices.

I hope you can help! Sticking thign into arrays and so on, if anyone wanted to suggest that, would be extremely difficult given the makeup of the existing site, which I did not build myself. Hence, a clever alteration to this SQL query itself, which I'm sure must be possible, would be much appreciated!

Hope to hear from you soon guys!

many thanks in advance!


SELECT creative_id FROM creative_group
0
Comment
Question by:m175400
[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
3 Comments
 
LVL 25

Accepted Solution

by:
imitchie earned 500 total points
ID: 20392701
SELECT DISTINCT(c.id)
FROM creative c, creative_group g, group_discipline gd
WHERE c.id = g.creative_id AND g.group_id = gd.id AND
( gd.id = '$disc' OR gd.map_ids = '$disc' /* new bit - select people who are in 'child' groups too */ )
AND c.visible = 1 AND c.active = 1
AND gd.id in (select top 3 group_id from creative_group cg1 where cg1.creative_id = c.creative_id order by pk_id)
ORDER BY g.status, c.boxed DESC, g.display_order, c.date_updated DESC, g.pk_id DESC

0
 
LVL 1

Expert Comment

by:Computer101
ID: 20962574
Forced accept.

Computer101
Community Support Moderator
0

Featured Post

 Watch the Recording: Learning MySQL 5.7

MySQL 5.7 has a lot of new features. If you've dabbled with an older version of MySQL, it is definitely worth learning.

Question has a verified solution.

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

When it comes to protecting Oracle Database servers and systems, there are a ton of myths out there. Here are the most common.
Azure Functions is a solution for easily running small pieces of code, or "functions," in the cloud. This article shows how to create one of these functions to write directly to Azure Table Storage.
Video by: Steve
Using examples as well as descriptions, step through each of the common simple join types, explaining differences in syntax, differences in expected outputs and showing how the queries run along with the actual outputs based upon a simple set of dem…
This is a high-level webinar that covers the history of enterprise open source database use. It addresses both the advantages companies see in using open source database technologies, as well as the fears and reservations they might have. In this…

631 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