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POMySQL SELECT combining 3 SELECTs INTO 1
 

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    <p>Consider following tables in MySQL database:</p> <pre><code>entries: creator_id INT entry TEXT is_expired BOOL other: creator_id INT entry TEXT userdata: creator_id INT name VARCHAR etc... </code></pre> <p>In <code>entries</code> and <code>other</code>, there can be multiple entries by 1 creator. <code>userdata</code> table is read only for me (placed in other database). </p> <p>I'd like to achieve a following SELECT result:</p> <pre><code>+------------+---------+---------+-------+ | creator_id | entries | expired | other | +------------+---------+---------+-------+ | 10951 | 59 | 55 | 39 | | 70887 | 41 | 34 | 108 | | 88309 | 38 | 20 | 102 | | 94732 | 0 | 0 | 86 | </code></pre> <p>... where <code>entries</code> is equal to <code>SELECT COUNT(entry) FROM entries GROUP BY creator_id</code>, <code>expired</code> is equal to <code>SELECT COUNT(entry) FROM entries WHERE is_expired = 0 GROUP BY creator_id</code> and <code>other</code> is equal to <code>SELECT COUNT(entry) FROM other GROUP BY creator_id</code>.</p> <p>I need this structure because after doing this SELECT, I need to look for user data in the "userdata" table, which I planned to do with INNER JOIN and select desired columns.</p> <p>I solved this problem with selecting "NULL" into column which does not apply for given SELECT:</p> <pre><code>SELECT creator_id, COUNT(any_entry) as entries, COUNT(expired_entry) as expired, COUNT(other_entry) as other FROM ( SELECT creator_id, entry AS any_entry, NULL AS expired_entry, NULL AS other_enry FROM entries UNION SELECT creator_id, NULL AS any_entry, entry AS expired_entry, NULL AS other_enry FROM entries WHERE is_expired = 1 UNION SELECT creator_id, NULL AS any_entry, NULL AS expired_entry, entry AS other_enry FROM other ) AS tTemp GROUP BY creator_id ORDER BY entries DESC, expired DESC, other DESC ; </code></pre> <p>I've left out the INNER JOIN and selecting other columns from <code>userdata</code> table on purpose (my question being about combining 3 SELECTs into 1).</p> <ul> <li>Is my idea valid? = Am I trying to use the right "construction" for this?</li> <li>Are these kind of SELECTs possible without creating an "empty" column? (some kind of JOIN)</li> <li>Should I do it "outside the DB": make 3 SELECTs, make some order in it (let's say python lists/dicts) and then do the additional SELECTs for userdata?</li> </ul> <p>Solution for a <a href="https://stackoverflow.com/questions/2374778/how-do-i-combine-these-sql-select-queries-into-one-select-statement">similar question</a> does not return rows where <code>entries</code> and <code>expired</code> are <code>0</code>.</p> <p>Thank you for your time.</p>
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