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    <pre><code>select a.itemId, a.name, b.itemId otherItemId, b.name othername from item a inner join item b on a.itemId &lt; b.itemId where not exists ( select * from vote v where ((v.betterItemId = a.itemId and v.worseItemId = b.itemId) or (v.betterItemId = b.itemId and v.worseItemId = a.itemId)) and v.userId = 1234) # &lt;&lt; enter the userId here order by rand() limit 1; </code></pre> <ul> <li>First generate all the a-b combinations, but use <code>a.id&lt;b.id</code> to prevent duplicates (e.g. 1-2 and 2-1).</li> <li>Next for each combination of a-b, check that (in any permutation better-worse or worse-better) the item has not already been voted by userId (example of <code>1234</code> in query)</li> <li>order all results randomly using <code>order by rand()</code></li> <li>use <code>limit 1</code> to get only 1 row</li> <li>In the select, show id and name for both items</li> </ul> <p>To show it as two separate rows, the front end should be used for this. But to do this purely in MySQL, a trick is required. The below is untested at the time of writing.</p> <pre><code>select ItemId, name from ( select a.itemId, a.name, @b := b.itemId from item a inner join item b on a.itemId &lt; b.itemId where not exists ( select * from vote v where ((v.betterItemId = a.itemId and v.worseItemId = b.itemId) or (v.betterItemId = b.itemId and v.worseItemId = a.itemId)) and v.userId = 1234) # &lt;&lt; enter the userId here order by rand() limit 1 ) c union all select itemId, name from item d on d.itemId = @b </code></pre>
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    1. COThis is working nicely. I should have specified in the question that I really could use two separate rows if possible, one for each item. Is there any way to integrate this?
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    2. COThat would be trivial to achieve from a front end? It will be tricky using mySQL
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