attribute-joinsmmqgisqgis
I've been trying to use the Attribute Join from CSV File function in MMQGIS, but it does not seem to work in Version 2.0.1. I've tried to join the same CSV and Shapefiles using V.2.0.1 running under both Ubuntu and Windows 7.
In each case, the procedure runs but returns no matches. It creates a new shapefile, but the file is empty. The same procedure with the same files works under QGIS 1.7.5.
Is this a known bug?
It's best if you make sure the two fields have the same data type.
The field type can't be changed for shapefiles. But it's easy to create a new empty text field and make that equal to the integer field.
You can use a field calculator expression that looks something like:
tostring( "INT_FIELD" ) and simply replace INT_FIELD with the name of the actual integer field.
You can easily change a CSV layer attribute value from text <-> number too.
If you are getting null values, you could try keeping the join, but just close and re-open that attribute table to see if the joined values are there (or even close/re-open QGIS).
I've been able to successfully join a csv to a shapefile with a mixture of field types so string vs integer shouldn't be the issue.
Looks like in order to get rid of the null values, they have to actually have a matching record in the corresponding table that joins are being made from. But in the image below, you can see that some do have a matching record:
I would do the following things to make life easier:
Before you do this, make a backup of your shapefile.
(choose no geometry) 
this is the Field tab I am referring to
Don't forget to toggle editing before and after deleting unnecessary field
Best Answer
Regarding the
Attribute Join from CSV Fileon http://michaelminn.com/linux/mmqgis/ it says that "CSV files must be encoded in the UTF-8 character set. Although other 8-bit encodings (like Windoze ISO-8859-x) will work if only ASCII characters are present, non-ASCII characters may cause unpredictable behavior".Could this be your case?
To
see / setyour character set encoding you can use Notepad++ like below: