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    <p>You should join your table and filter the result with HAVING keyword :</p> <pre><code>SELECT games.game, COUNT(games.ga_id), ga_eq.eq_id FROM `games` JOIN ga_eq USING (ga_id) JOIN equipements USING (eq_id) GROUP BY games.ga_id HAVING COUNT(games.ga_id)=1 AND eq_id=1 </code></pre> <p>Here is the method : Get all row with </p> <pre><code>SELECT games.game, ga_eq.eq_id FROM `games` JOIN ga_eq USING (ga_id) JOIN equipements USING (eq_id) </code></pre> <p>result : <img src="https://i.stack.imgur.com/oOUoQ.png" alt="enter image description here"></p> <p>Then grouby ID and make a count a number id (so number equipement)</p> <pre><code>SELECT games.game, ga_eq.eq_id, COUNT(games.ga_id) FROM `games` JOIN ga_eq USING (ga_id) JOIN equipements USING (eq_id) GROUP BY games.ga_id </code></pre> <p><img src="https://i.stack.imgur.com/VkZWg.png" alt="enter image description here"></p> <p>Then use HAVING keyword to keep only games with one equipement and put your eq_id filter IN HAVING CLAUSE (not in WHERE clause)</p> <pre><code>SELECT games.game, ga_eq.eq_id, COUNT(games.ga_id) FROM `games` JOIN ga_eq USING (ga_id) JOIN equipements USING (eq_id) GROUP BY games.ga_id HAVING COUNT(games.ga_id)=1 AND eq_id=1 </code></pre> <p>Result : <img src="https://i.stack.imgur.com/H442f.png" alt="enter image description here"></p> <p>Change the filter <code>AND eq_id=3</code> -> empty result</p> <p>For many equipment id the query is a little bit different, I try to make one generic but didn't fint out, if someone else have an idea ?</p> <pre><code>SELECT g.game, equipements.eq_id, ( SELECT COUNT( eq_id ) FROM ga_eq WHERE ga_id = g.ga_id AND eq_id IN (1, 2) ) AS nb_eq FROM `games` g JOIN ga_eq USING ( ga_id ) JOIN equipements USING ( eq_id ) GROUP BY game HAVING nb_eq =2 </code></pre> <p>You have to change <code>AND eq_id IN (1, 2)</code> AND <code>HAVING nb_eq =2</code> to change the input</p>
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    1. USMarcassin
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    1. COthanks a lot for your help. You did a very good job explaining in detail how this query solves my problem.
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    2. COHi Marcassin, what about if my inputs are eq_id 1 and 2 and the expected return should be ga_id 1 which is basketball, What should be the query?
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    3. CO@user2322606 just edited the answer. Find a generic function could be a good training.
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