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POUnique Columns with MySQL Union
 

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  1. POUnique Columns with MySQL Union
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    <p>I've got a mysql query that is returning the required data, but is not returning unique rows. How can I assure that only unique rows are returned?</p> <p><strong>Here is my query</strong></p> <pre><code>SELECT a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image FROM followers a INNER JOIN donors b ON a.user_id = b.user_id WHERE following = 257 UNION DISTINCT SELECT a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image FROM followers a INNER JOIN donors b ON a.following = b.user_id WHERE a.user_id = 257 </code></pre> <p>Which returns multiple results for a user_id. How can I make sure that the results are not doubled up, by user_id?</p> <p>I have tried a group by, but I must be doing something wrong, cause I can't get it working.</p> <p>The results I get back</p> <pre><code>**follow_id user_id following donor_id firstname lastname** image 13 224 257 124 Just A Donor 224.jpg 11 257 224 124 Just A Donor 224.jpg 9 257 222 116 Dummy Donor 222.jpg </code></pre> <p>Got it...just had to group by donor_id</p> <pre><code>SELECT * FROM (SELECT a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image FROM followers a INNER JOIN donors b ON a.user_id = b.user_id WHERE following = 257 UNION DISTINCT SELECT a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image FROM followers a INNER JOIN donors b ON a.following = b.user_id WHERE a.user_id = 257 ) AS t GROUP BY donor_id </code></pre>
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    1. USCarl Weis
    1. USCarl Weis
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    1. COAre you now saying you want just one row per user id? That's different from the question you originally asked (and which 2 people answered). How should the query decide which row to return, for any given user id? For example, in the result set you gave, which of the two rows of the result should be returned for user_id 257?
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      1. POUnique Columns with MySQL Union
      1. USDawood ibn Kareem
    2. COWhen the user_id is the same (257) what would you want to show for the other columns (that are different as you show). Best of all please show the **desired** output you want to see. Thanks!
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      1. POUnique Columns with MySQL Union
      1. USMichael Durrant
    3. COIt should only return 1 row, per user_id. Sorry if my question was not clear.
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      1. POUnique Columns with MySQL Union
      1. USCarl Weis
 

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