attribute-tablefield-calculatorqgis
I have about 19000 records, I added new column and I would like to fill it with string values (eg. brand)- same value for all rows.
I'm not considering copy/paste. I know I could do it with exporting to .csv or something and edit it excel, but that feels a bit… lame and unmethodical?
So, any smart solutions?
The short answer is YES!. That is the power of the calculator. In the attribute table, make your selection (directly on the map, selecting rows in the table or many other different ways). Please make sure that you are in an edit session so that your changes can be undone. If outside an edit session, you have to live with (or fix) your mistakes.
Right click on column name at the top to open the calculator. In the window that pops up, enter your value between quotation marks and select OK. This will automatically fill that value in that column for all the features/rows that are selected.
For more options, learn how to use the python radio button,
Here is a tips and tricks pdf to help.
This resource will help with some automation. and can also be accessed from the right click on the column.
there are some nice links if you hit google
There are more elegant ways to do this with joins, etc., but as an ad-hoc one off, one simple approach that should work is:
Export the original layer as a csv, but making sure under Layer Options you get the geometry exported AS_WKT. Your csv file should now consist of one line per feature, with the feature attributes as column, plus an extra first column called WKT representing the feature geometry as a text string in your chosen CRS.
You or others can change, even add/subtract rows, in Excel. Keep the column names (=attribute names) unchanged. You can theoretically change the geometry by editing the WKT string, but this is unlikely to be useful.
Import the edited csv as delimited text, making sure the importer Geometry Definition is set to WKT and pointed at the WKT field (which should be automatic). Make sure the geometry CRS is the same used for the export.
Re-export the imported csv layer in your desired spatial file format (shapefile if you must, or into a geopackage or whatever), probably the same as the original format.
Use the changeLayerSource plug-in to repoint the original layer at the new file from the previous step. If you indeed did not change the layer names, your styling etc will be preserved.
The above will implicitly (by sliding the new file in place of the old file) replace all of the old features with the edited ones, and so won't create duplicates. However, it also carries risks - you could munge stuff you didn't intend to touch if you're careless. If you need to be fancier, for instance you want to treat new features, updated features, and deleted features differently, then you will have to creatively use joins, or SQL.
The important elements for success above are to handhold QGIS to make sure the geometry is exported and then reimported, to make sure the CRS stays the same, and to ensure the data attribute names / column labels are unchanged.
Best Answer
Use the Field Calculator. If your column is empty and it has to be filled with the string "mystring" you need to select all the rows of your attribute table and than use the replace function: