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    <p>Try this solution:</p> <pre><code>SELECT a.product_group, SUBSTRING_INDEX(GROUP_CONCAT(a.manufacturer ORDER BY a.occurrences DESC SEPARATOR ':::'), ':::', 1) AS manufacturer_mode FROM ( SELECT aa.product_group, aa.manufacturer, COUNT(*) AS occurrences FROM products aa GROUP BY aa.product_group, aa.manufacturer ) a GROUP BY a.product_group </code></pre> <h1>Explanation:</h1> <p>This still uses a form of subquery, but one which executes only once as opposed to one that executes on a row-by-row basis such as in your original example.</p> <p>It works by first selecting the <code>product_group</code> id, the manufacturer, and the count of how many times the manufacturer appears for each particular group.</p> <p>The <code>FROM</code> sub-select will look something like this after execution (just making up data here):</p> <pre><code>product_group | manufacturer | occurrences --------------------------------------------------- 1 | XYZ | 4 1 | Test | 2 1 | Singleton | 1 2 | Eloran | 2 2 | XYZ | 1 </code></pre> <p>Now that we have the sub-select result, we need to pick out the row that has the maximum in the <code>occurences</code> field for each product group.</p> <p>In the outer query, we group the subselect once again by the <code>product_group</code> field, but this time, <strong><em>only</em></strong> the <code>product_group</code> field. Now when we do our <code>GROUP BY</code> here, we can use a really compelling function in MySQL called <code>GROUP_CONCAT</code> which we can use to concatenate the manufacturers together and in any order we want.</p> <pre><code>...GROUP_CONCAT(a.manufacturer ORDER BY a.occurrences DESC SEPARATOR ':::'... </code></pre> <p>What we are doing here is concatenating the manufacturers together that are grouped together per <code>product_group</code> id, the <code>ORDER BY a.occurrences DESC</code> makes sure that the manufacturer with the most appearances appears <strong><em>first</em></strong> in the concatenated list. Finally we are separating each manufacturer with <code>:::</code>. The result of this for <code>product_group</code> <code>1</code> will look like:</p> <pre><code>XYZ:::Test:::Singleton </code></pre> <p><code>XYZ</code> appears first since it has the highest value in the <code>occurance</code> field. We <em>only</em> want to select <code>XYZ</code>, so we encase the concatenation within <code>SUBSTRING_INDEX</code>, which will allow us to only pick the first element of the list based on the <code>:::</code> delimiter.</p> <p>The end result will be:</p> <pre><code>product_group | manufacturer_mode --------------------------------------- 1 | XYZ 2 | Eloran </code></pre>
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    1. POMode calculation without a subquery field in MySQL?
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    1. COThe `SUBSTRING_INDEX(GROUP_CONCAT(` is really ugly but I really like the way it's used to answer the question. +1 :p
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    2. COBy the way, the case of equal occurences for a same product is not handled here isn't it ?
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    3. CO@OlivierCoilland, the question did not state how equal occurrences should be handled. Right now if there are any, it would just select the first one to come up. Perhaps the OP would like to then order it based on an additional field, which would just involve adding another field to the `GROUP_CONCAT()` `ORDER BY`.
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