1

Can anyone suggest how I can change the length of an existing column (For ex. column name -- ABCD, column_Type -- Text, Length -- 254). It would be great to have solution on platforms like ArcGIS or QGIS.

  • Are you referring to the column name or the amount of characters you can input as a feature? – Joseph Jun 12 '15 at 11:57
  • i am referring to the amount of characters to put in it . – ashish kumar Jun 12 '15 at 11:58
  • Some GIS platforms could potentially handle a Memo type field to extend past the 254 characters. I would assume that QGIS could potentially be able to handle it (unsure) as I know ArcMap cannot. The other issue would be availability to share the data doing this. ThinkGeo's .NET tools supports larger types, but it converts the DBF to a more FoxPro style which doesn't work for other GIS programs. – Branco Jun 12 '15 at 14:15
1

In QGIS it is worth to say that it is not possible to change field width (if we are talking about shapefiles) for existing columns. But it is really easy to create new column with needed length and copy content into that column from the old one. You can do that with Field calculator. For renaming / reordering / adding multiple fields etc. there is great plugin called table manager - https://plugins.qgis.org/plugins/tablemanager/.

If you don't need to change the column length but only shorten the string you can use Field calculator again. For example for column named Title first 10 characters:

substr(Title,1,10)

And this question is almost dupplicate of - How to change field length in QGIS - you can alter column length in dbf files (the tabular data connected to shapefile) in OpenOffice Calc - as advised in comment below this has some strict limitations and can lead to integrity/file corruption.

Also as advised by other comment if you need to go over limit - maximum length (for example text 254 (256)) specified for shapefile (respectively linked dBase file) data type, you need to use different format (like SpatiaLite, PostGIS etc.), there is no other way around:

Maximimum length of text fields in shapefile and geodatabase formats?

  • 2
    I suspect the OP wants to increase the field width of a shapefile beyond the 254 permitted by the dBase format. You didn't mention that the new column cannot exceed the maximum of the format (which varies by source and datatype). – Vince Jun 12 '15 at 13:44
  • 2
    I also question the wisdom of discussing the option of altering the .dbf with Office tools without mentioning the possibility of corruption of the shapefile if row order or count is altered in any way (or recommending caution and backup procedures before making such changes) – Vince Jun 12 '15 at 13:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.