There is a polygon layer 'Union23' that was created with the "Union" tool.
Layer's attribute table includes the following values.
My effort is simply to aggregate those polygons by
"FLAECHEID" field with the sum and count of a field
"In_Value1" via a Virtual Layer. So I am using the expression:
SELECT *, SUM(In_Value1), COUNT(In_Value1) FROM Union23 GROUP BY "FLAECHEID"
However, I am getting really weird output and I do not understand why I am losing a part of geometry on the way? Any suggestions?