[Qgis-user] Ratio vector classification question (QGIS Desktop 2.12.1 with GRASS 6.4.3)

[John Charde]

Hi all,

I am following the QGIS training guide (complete with datasets it had me
download) and am working with vector classifications. After the guide
prompted me create a nominal classification of the "landuse" layer, it went
into ratio classification. I added an AREA column to the attribute table,
and used the attribute calculator to find the areas of all attributes (with
the "type" box set as "decimal number"). I changed the classification style
to "Graduated," changed the "column" to AREA, created my own color ramp and
classified the data. after I clicked "OK" through the prompts to get back
to the main screen, I tried to save the style and toggle off editing, and I
got an error stating the following:

Could not commit changes to layer landuse


Errors: ERROR: 1 new attribute(s) not added

ERROR: 55 attribute value change(s) not applied.

Provider errors:

SQLite error: duplicate column name: AREA

SQL: ALTER TABLE "landuse" ADD COLUMN "AREA" FLOAT

SQLite error: near "WHERE": syntax error

SQL:



I'm not sure what it means and what I am supposed to do to rectify the
situation. Could anyone help me? I greatly appreciate it!


Best,


      Jack C. (new QGIS user)
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