I've categorized multiple points for schools that are to be developed, reconstructed or demolished, with green, yellow and red colors if the schools capacity (the number of children) is increasing, staying the same or decreasing. The size of each point is data defined depending on how large the change in capacity is.

However, for some of the schools the changing capacity is unknown, and therefore 'NULL' in my attribute table for these schools. I'm looking for a way to give these schools a Star symbol instead of the circles, so that their size is not to be confused with the schools where the change in capacity is known.

QGIS, v 2.14. In Layer properties - Style I've categorized them as stated earlier. To give the ones with a known change of capacity a circle and the ones with unknown change of capacity (= NULL) a star symbol i tried the following so far with no success: in Layer properties - Style - Symbol Change-button, I added 2 Simple markers. 1st one a circle and 2nd one a star. In each one I then went to Data defined override - Edit, command: "Change_cap" is NULL and in the second one: "Change_cap" is NOT NULL However, it's still showing both markers instead of just one of them (depending on if change of capacity is known)

Attribute table

So far how I tried to solve it

  • 3
    What program and version are you using?
    – GISHuman
    Mar 9, 2017 at 16:13
  • 1
    Welcome to GIS SE! As a new user please take the tour to learn about our focused Q&A format. Please edit your question to include which GIS software and version you are using, and some information about what you've tried.
    – Midavalo
    Mar 9, 2017 at 17:26

1 Answer 1


Since you need to follow some specific rules, I would try to use a Rule-based renderer instead of a Categorized renderer.

You need to create 6 rules like these ones:

enter image description here

The above rules are reported in the following and with the same order showed in the attached image (remember that you may copy-and-paste them instead of creating each one from the beginning):

"Descript" = 'Demolish' AND  "abs_change" is not NULL
"Descript" = 'New school' AND  "abs_change" is not NULL
"Descript" = 'Rebuild' AND  "abs_change" is not NULL
"Descript" = 'Demolish' AND  "abs_change" is NULL
"Descript" = 'New school' AND  "abs_change" is NULL
"Descript" = 'Rebuild' AND  "abs_change" is NULL

Once you have set the right symbol and size for each rule, you will obtain this result and, as expected, only one symbol is shown:

enter image description here

  • 1
    Great! I would still leave it as a feature request though, to be able to use different symbols in "catagorised mode". Maybe it's already possible to do it, but I couldn't make it work. Thanks a lot for the help! Mar 23, 2017 at 15:23
  • @djohansson85 I'm glad it worked also for you! However, the best way to say 'thanks' is by accepting the answer, if it solved your issue. =)
    – mgri
    Mar 23, 2017 at 16:15
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    Obviously new in the forum. Great feedback. Solved! :) Mar 24, 2017 at 6:42

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