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I have a table with a series of objects in it. Each record has a reference number but these numbers are NOT unique - e.g. there are two records with reference "01" and each of them has a different object attached.

I would like to combine all objects with the same reference number into a collection object so that I can attach these collection objects to a different table. I should end up with one row per reference number with no duplicates and without losing any of the objects.

I could use "Objects combine" but this will do a geographic union which is not appropriate - some sites are subsections of sites with the same reference number.

The documentation for the "Create collection" statement only shows it being used to create objects.

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I have exactly the same problem and I'm finding the Mapinfo documentation on Collection Objects to be minimal to say the least. Did you get anywhere with them or have you given up? Best wishes Annette – user10022 Sep 6 '12 at 16:09
Hmmm I changed jobs a few months back and haven't touched Mapinfo since then so it's a bit fuzzy but I think I just worked around the problem. The answers below were IIRC helpful but not quite right, else I'd have accepted one. Sorry I can't be more help! – Mr_Chimp Sep 19 '12 at 22:46

I thought you might be able to do it using SQL, but it seems Mapinfo doesn't allow you to combine geometries using SQL - Manifold, which I've also used, does.

One way may be to convert the table file into a database (SQLite or PostGIS), possibly using QGIS and then perform an aggregate ST_Collect query grouping by reference number

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Have a look at the feature Combine Objects using column that you can find in the Table menu. That will help you merge records with the same value into a single record (in a new table)

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