Question

I have an input box where users can enter tags when they ask a question. They are separated by commas, like this:

test1, test2, test3, test4

My questions table structure is:

To show the tags of a question I just use explode(",", $qinfo['tags']) and then a foreach loop.

But, I don’t know how I can display tags from most popular to least popular on a separate “popular tags” page.

Thanks for any help!

Answer 1

You should create tags and questions_tags table.

tags
----
id
name

questions_tags
-------------
id
question_id
tag_id

And get tags sorted by popularity:

SELECT t.id, t.name, COUNT(qt.id) AS total
FROM tags t
LEFT JOIN questions_tags qt ON t.id=qt.tag_id
GROUP BY t.id, t.name
ORDER BY total DESC

But I suggest you to keep the tags field in the questions table. Use it for caching. eg: if you’re displaying a single question, no need to query the tags and questions_tags table.