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Editorial Team
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Asked: 2026-06-08T13:35:52+00:00

Hi friends i am listing topics in php which may be associated with multiple

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Hi friends i am listing topics in php which may be associated with multiple category

my db schema is

topics

topic_id
user_id
topic_name

category 

category_id
category_name


topic_category (for association)

tc_id
topic_id
category_id

topic_response // for results

tr_id
topic_id
response ( given in a form of 5 star rating so its in range of 1-5 always )
user_id

what i need to do is

1st ) list top ten topics based on responses ya it will be based on count of responses

i tried ->

select t.* ,count(tr.response) as votes from topics t , topic_response tr where t.topic_id=tr.topic_id group by tr.topic_id order by votes LIMIT 10

not working

2nd) user will be shown list of topic . he can choose the category in which he wants that can be multiple too.

for example

if he chooses category_id 1,2,3,4 then topics listed in this category will be listed.

i have tried to

select t.* from topics t ,topic_category tc where tc.topic_id = t.topic_id and category_id IN (1,3,2,4) 
// not able to get idea on this i would prefer if i could do this in subquery since i also need to check if the user has already responded to that question .

**3) in case if i get a query working suppose .

from php side i will be getting an array of category_id from select multiple dropdown
like array(1,2,3,4)

so i was thinking how will make this query accept category id

in form of category_id IN (1,3,2,4) in mysql query**

**can i directly pass an array like

category_id IN ($ids) where $ids is an array**

i am a newbie in mysql please help me
you help will be appreciated 🙂

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1 Answer

  1. Editorial Team

    For the first question:

    You have to use LEFT JOIN and match (response’s topic id row) to (topic’s id) then count(response’s topic id) and GROUP everything by (response’s topic id).

    for example:

    Responses Table = responses

    response_id

    topic_id

    response_message

    Topics Table = topics

    id

    title

    content

    The query is

    SELECT topics.title,topics.content,COUNT(responses.topic_id) AS count FROM topics
    LEFT JOIN responses ON topics.id = responses.topic_id GROUP BY count LIMIT 10

    For question 2:

    1. You can try using AND ( IN 1 OR 2 OR 3 OR 4
    2. You can try using BETWEEN 1 AND 4
    3. WHERE(category_id>=1&&category_id<=4)
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