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POMySQL Many-to-Many Relationship Select Conditions
 

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    <p>I have two tables books and tags which are in a many-to-many relationship via the table books_tags. What I want to do is select all books that have one or more tag(s) like '%tag%'. No problem. However, I also have a group_concat field which I want to be filled with all the tags that are related to the selected book.</p> <p>My select query basically looks like this:</p> <pre><code>select flbdb_books.id, flbdb_books.title, flbdb_tags.id, flbdb_tags.name, group_concat(distinct concat('["', flbdb_tags.id, '","', flbdb_tags.name, '"]') separator ',') as tags from flbdb_books join flbdb_books_tags on flbdb_books.id = flbdb_books_tags.book_id join flbdb_tags on flbdb_tags.id = flbdb_books_tags.tag_id group by flbdb_books.id; </code></pre> <p>This delivers the desired result if I don't have any conditions. I use PHP and json_decode to read the tags field. I have tried three different ways to filter the results, but none of them works.</p> <ol> <li><p>use where:</p> <p><code>where flbdb_tags.name like '%poetr%'</code></p> <p>however, this means that the tags field (the one that is assembled using group_concat) is only filled with this tag</p></li> <li><p>use having</p> <p><code>having flbdb_tags.name like '%poetr%'</code></p> <p>this does not return all books tagged poetry, because in some cases the poetry tag is hidden behind another tag due to the group by</p></li> <li><p>use having on the group_concat field</p> <p><code>having tags like '%poetr%'</code></p> <p>this would actually do the trick, but I need to do the case-insensitive searching, and upper(tags) doesn't work</p></li> </ol> <p>I hope it is clear what I want to do.</p> <p>Thanks</p>
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    1. USflammel
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    1. COWhy doesn't your #3 solution work? doing a like search like that is case-insensitive to begin with. There is no difference between using `'%poetry%'`,`'%POETRY%'`, or even `'%pOeTrY%'`
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      1. USBrian Glaz
    2. COThis may be a good case to use `inner_join`.
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    3. CO@Brian I don't know why, but like is not case-insensitive in this case. Maybe it's because of the group_concat?
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