How to delete duplicate records in MySQL by retaining those fields with data in the duplicate item b

Posted by NJTechGuy on Stack Overflow See other posts from Stack Overflow or by NJTechGuy
Published on 2010-04-09T18:05:10Z Indexed on 2010/04/09 18:23 UTC
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duplicate-removal

I have few thousands of records with few 100 fields in a MySQL Table.

Some records are duplicates and are marked as such. Now while I can simply delete the dupes, I want to retain any other possible valuable non-null data which is not present in the original version of the record. Hope I made sense.

For instance :

a b c d e f key dupe
--------------------
1 d c f k l 1   x
2 g   h   j 1    
3 i   h u u 2
4 u r     t 2   x

From the above sample table, the desired output is :

a b c d e f key dupe
--------------------
2 g c h k j 1
3 i r h u u 2

If you look at it closely, the duplicate is determined by using the key (it is the same for 2 records, so the one that has an 'x' for dupe field is the one to be deleted by retaining some of the fields from the dupe (like c, e values for key 1).

Please let me know if you need more info about this puzzling problem.

Thanks a tonne!

p.s : If it is not possible using MySQL, a PERL/Python script sample would be awesome! Thanks!

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