attribute-tablecalculate-valuesqgis
I'm trying to figure out how to display one attribute column in percentages. I've created a new field inside the attribute table and proceeded with:
concat("column with numbers to be changed in percentage", '%')
But the output displays NULL. Any insight on what I may be doing wrong?
If it's just for visualization you could use the geometry generator with the same expression:
geom_from_wkt("WKT")
To set it up you may duplicate your layer (so you will get one layer with the original geometry and the copy with the geometry from the WKT) or add a new symbol layer to display both geometry in original layer. Then in the Layer styling panel use the below setting (Symbol layer type : Geometry Generator ; Geometry type : Point/Multipoint):
Alternatively you can use the processing tool "Geometry by expression" (using again the same expression) but this will create a new layer so change on the original layer wont be reflected in this.
EDIT : If you have no geometry in the original layer the best solution is to create a virtual layer based on your table where your SQL query generate the geometry from the WKT column, this way you get a layer that will stay synchronized with the original data.
You may adapt this to get the layer (replace : "Field &" , ... , "Field n" by the name of the field you want to get and mysql_TABLE by the name of your table)
SQL query :
SELECT "Field &" , ... , "Field n" , st_geomfromtext( "WKT") as geometry FROM mysql_TABLE
Best Answer
Given decimal values in a double precision column (or other), you can use an expression to:
In a label expression, this is what I would do:
(my percent column is called "rating")
I use the label expression rather than creating a new column of otherwise redundant data.
Here I've added both the original column and the percent-formatted column on two lines of the label: