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I am new to MapInfo and I need to combine several tables together, by copying and pasting. I need for all the tables to have the same table structure, however when I try to modify these tables (table>maintenance>table structure>view/modify table) it won't allow me to change the order of the fields. When i try to, i get the following error: "cannot perform this operation on table (table name)." Why won't it let me change the data structure? any suggestions?

The picture is of the dialogue window i get when i attempt to modify table structure. As you can see, it doesn't look like the regular window. But i don't know why or how to change it.
When i move my fields to the order I need them in, and click OK, is when i get the error message.

This is the dialogue window i get when i attempt to modify

THanks!

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  • I suspect the table is read only (probably because of table joins) - can you try File>save copy as... to create a fresh table and then open the new table and re-trying your steps for re-ordering the columns?
    – Mark
    Commented Sep 11, 2014 at 15:30

3 Answers 3

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MapInfo has a limit of 4096 characters per row (see http://testdrive.mapinfo.com/techsupp/miprod.nsf/kbase_by_product/BC5DE25962BC57C285256278002FB800). From your screenshot I suspect that your table structure may exceed this limit.

Certain third party utilities which work with tab files have worked around this deficiency in MapInfo, so depending where you're sourcing your data this may be the issue...

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  • I have another table that i uploaded to the same mapper. Its is compilation of all the other tables, edited in excel, so it is the largest of all the tables. and im able to modify the structure of that one. So i don't think its the table size that's the problem. I need to use the building footprints that are associated with the original tab files, so i am unable to use the table that I compiled in Excel. Any other suggestions?
    – Patricia Hernandez
    Commented Sep 10, 2014 at 21:50
  • Where did you source the tab files? Have they been run through another program before pulling into MapInfo (eg, OGR tools)?
    – ndawson
    Commented Sep 10, 2014 at 22:20
  • the tab files i'm using are copies of the original tab files, which came from my local C drive. they have not been run through any other program or modified in any way. they are the original, and I am working on a copy of those. I was working on them yesterday and day before, and i was able to arrange my fields as I needed them, by using the "up" "down" buttons in the "modify" table window. At some point the "modify table" window changed, and i started getting that error message, and have been unable to modify structure since. I have no idea why. Any help is appreciated!
    – Patricia Hernandez
    Commented Sep 10, 2014 at 22:32
  • What about packing the table? (Data -> Maintenance -> Pack Table). Does that help?
    – ndawson
    Commented Sep 11, 2014 at 1:02
  • The limitation of 4,096 characters per row in a tab file has been extended to 64,500 characters (or bytes ) in MapInfo Professional 12.0
    – Peter Horsbøll Møller
    Commented Sep 12, 2014 at 8:42
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I suspect the table is read only (probably because of table joins) - can you try File>save copy as... to create a fresh table and then open the new table and re-trying your steps for re-ordering the columns?

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Close the tab file in MapInfo and navigate to it in windows explorer. Now open the .TAB file in notepad and look for a line that says "\IsReadOnly" = "TRUE". It should be right at the bottom of the tab file in the metadata. If it says 'TRUE' then change it to 'FALSE' and save the tab file. Re-open in MapInfo and with any luck you should be able to make your changes.

If it doesn't say TRUE then I would suggest following Mark's suggestion and saving off a new copy of the table.

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