Question

I’m using a PHP script and MySQL to diplay some values from a table, but I’m really stuck, I have searched around the web but I can’t really express my question

My table looks like:

Table : Tags

Id  Tag  ArticleID
1    1    100
2    1    200
3    2    90
4    2    100
5    3    100
6    5    90
7    6    90
8    10   100

The Id column is the primary key.

So I want to make a Select statement that it will display which ArticleIDs have used of the tags

Example:

• For Tags: 1 and 2 The ArticleID that contains this tags is 100
• For Tags: 1,2 and 3 The ArticleID that contains this tags is 100
• For Tags 1 and 5 There are no articles that contain these tags

Any help?

Also is there any way to make combinations with the above statement ?

Example:

• For Tags: 1,3,6 and 5 There are no articles that contain these tags
• BUT For Tags: 1 and 3 The article ID that contains this tags is 100,
• For Tags: 5 and 6 The article ID that contains this tags is 90 etc..

Answer 1

It’s a horrible hack, but this is what I could come up with:

<?php
$tags_to_check = array(1,2,3);

mysql_query(
  'select distinct t1.articleid from tags t1 where (
     select count(distinct(tag)) from tags t2 where
       t2.articleid = t1.articleid and
       t2.tag in '. implode(',', $tags_to_check) .')
   )='. count($tags_to_check);
?>

for each article, I count how many unique tags it has that are in the given set (1,2,3), if that number is 3, we know the article contains all the requested tags.