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POCreate toplist with unique users
 

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    <p>I have a table with the fields <code>id, user_id, condition1, condition2, condition3, score</code>. And each user can have several rows in the table. What I want to do now is to create several toplists. It could be for example a toplist where <code>condition1 = foo</code> and I only want to count each user once but I want the complete best row from each user.</p> <p>So <code>SELECT user_id, MAX(score) AS s FROM table WHERE condition1 = foo ORDER BY s DESC LIMIT 50</code> don't work.</p> <p>There are so many different toplists I want so creating a second table where I store the users best result isn't really an option. Because each user would probably have more then 100 different best results.</p> <p>The two things that are important is that getting the top 50 i quick. But also getting which place a specific user is placed on (which is pretty easy by just checking how many unique users have a bigger score than the specific user).</p> <p><strong>Update:</strong> I tested both Thomas and Quassnoi ideas and Thomas idea took 11 seconds and Quassnoi took 4.5 seconds.</p> <p>Then I figured out another way to do it which is:</p> <pre><code>SELECT ( SELECT id FROM table AS ti WHERE ti.user_id = t.user_id AND condition1 = foo ORDER BY score DESC LIMIT 1 ) FROM table as t WHERE condition1 = foo GROUP BY user_id ORDER BY MAX(score) DESC LIMIT 50 </code></pre> <p>And then I just make another query where a pick out all rows <code>WHERE id IN(all ids returned from the first query)</code> and this way takes 0.4 seconds.</p> <p>Is this a good way of doing it or am I just lucky in my testdata?</p>
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