title: How to modify attribute table in QGIS
body: <p>I'm trying to create a global map grouping countries by some criteria, in QGIS, I download one template with all countries, and I'm trying to update this dataset.
  I opened attributes table --> edit -->add column, and after I choose the calculator opcion and I use if "id country" = "US" then 1, "id country" = "GB" then 2.... etc
  and after I save this table, but when I try to close and open the same table I see that the changes are not saved, and I can't use after this.</p>
  
  <p>Do you know how can I save this changes permanently to use this new column in categorizing by colors?</p>