Question

I am working on a search/tag system. My original query I wrote was for when I was storing ‘title’, ‘description’ and a comma seperated ‘tags’ column in my article/video table. I have since realised the advantage of normalising my tags. I now have three table to deal with…

tbl_Articles

• article_id
• title
• description
• content

tbl_tag_index

• tag_id (surrogate primary id)
• tag_type (equals 1 for tbl_Articles,
  2 for tbl_videos)
• tag_word_id (see table bellow)
• tag_target_id (article_id/video_id –
  depends on tag_type)

tbl_tag_word

• tag_word_id
• tag_word (finally the actual tag)

This query returns the tags… only problem is it returns them as different rows. I guess I would need the results to be grouped to the same row so that my search query may work

SELECT * 
  FROM `tbl_articles` A 
  JOIN `tag_index` I ON A.article_id = I.tag_target_id 
  JOIN tag_word W ON I.tag_word_id = W.tag_word_id 
 WHERE I.tag_type_id = 1

Here is my old search query

SELECT *, 
(
(CASE WHEN `description` LIKE '%hotel%' THEN 1 ELSE 0 END) + 
(CASE WHEN `description` LIKE '%london%' THEN 1 ELSE 0 END) + 
(CASE WHEN `description` LIKE '%lazy%' THEN 1 ELSE 0 END) + 
(CASE WHEN `description` LIKE '%dog%' THEN 1 ELSE 0 END) +

(CASE WHEN `title` LIKE '%hotel%' THEN 1 ELSE 0 END) + 
(CASE WHEN `title` LIKE '%london%' THEN 1 ELSE 0 END) + 
(CASE WHEN `title` LIKE '%lazy%' THEN 1 ELSE 0 END) + 
(CASE WHEN `title` LIKE '%dog%' THEN 1 ELSE 0 END) +

(CASE WHEN `tags` LIKE '%hotel%' THEN 1 ELSE 0 END) + 
(CASE WHEN `tags` LIKE '%london%' THEN 1 ELSE 0 END) + 
(CASE WHEN `tags` LIKE '%lazy%' THEN 1 ELSE 0 END) + 
(CASE WHEN `tags` LIKE '%dog%' THEN 1 ELSE 0 END)

) AS relevance
FROM `tbl_Articles`
WHERE `description` LIKE '%hotel%'
  OR `description` LIKE '%london%'
  OR `description` LIKE '%lazy%'
  OR `description` LIKE '%dog%' 
  OR `title` LIKE '%hotel%'
  OR `title` LIKE '%london%'
  OR `title` LIKE '%lazy%'
  OR `title` LIKE '%dog%'
  OR `tags` LIKE '%hotel%'
  OR `tags` LIKE '%london%'
  OR `tags` LIKE '%lazy%'
  OR `tags` LIKE '%dog%'
ORDER BY relevance DESC
LIMIT 0 , 10;

Answer 1

Use:

SELECT A.*, 
       GROUP_CONCAT(DISTINCT w.tag_word ORDER BY w.tag_word ASC SEPARATOR ',') AS tags,
       COUNT(DISTINCT w.tag_word) +
       (CASE WHEN `description` LIKE '%hotel%' THEN 1 ELSE 0 END) + 
       (CASE WHEN `description` LIKE '%london%' THEN 1 ELSE 0 END) + 
       (CASE WHEN `description` LIKE '%lazy%' THEN 1 ELSE 0 END) + 
       (CASE WHEN `description` LIKE '%dog%' THEN 1 ELSE 0 END) +

       (CASE WHEN `title` LIKE '%hotel%' THEN 1 ELSE 0 END) + 
       (CASE WHEN `title` LIKE '%london%' THEN 1 ELSE 0 END) + 
       (CASE WHEN `title` LIKE '%lazy%' THEN 1 ELSE 0 END) + 
       (CASE WHEN `title` LIKE '%dog%' THEN 1 ELSE 0 END) AS relevance
  FROM tbl_articles A 
  JOIN tag_index I ON A.article_id = I.tag_target_id 
  JOIN tag_word W ON I.tag_word_id = W.tag_word_id 
 WHERE I.tag_type_id = 1
   AND w.tag_word IN ('hotel', 'london', 'lazy', 'dog')
GROUP BY a.article_id, a.title, a.description, a.content
ORDER BY relevance DESC