Ordering query result by field from a different table (MySQL)

Question

I have a MySQL table structure and need to get a specific query working but I just can\'t wrap my head around it somehow. First off, here\'s the relevant table structure.

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Answer 1

If you would like to avoid duplicates, you can use group by on the date:

SELECT f.id, STR_TO_DATE(w.werte, '%d.%m.%Y') as d 
 FROM folders f JOIN werte w
 ON w.folder_id = f.id
 GROUP BY d
 ORDER BY d;