I am new to GIS systems and am beginning with CartoDB. I have extracted polygon data from Open Street Map which I have uploaded and added as a dataset. The data shows building footprints but these seem to disappear into another poloygon(?) which shows the broader site boundaries; in essence everything is highlighted bar the roads when what I actually want is only the building footprints highlighted.
Anyway, in the table I have a lot of rows where the value in the building column is null. When I use the filter to switch this off, I achieve what i need. However, this is only possible when viewing the list layout (I just switch off null) because for city size data it says too much data to view as a list so I have to search to filter if that makes sense and I'm not sure how to switch it off this way?
I have also tried a basic SQL query on the table which did not seem to work:
SELECT * FROM map_table; DELETE FROM map_table WHERE building = "null";
I'm new to programming so probably making some basic errors but if someone could shed some light or point me in the right direction?