How to make an intersection function condition for a field calculator?I have three layers-buildings, parcels_old, parcels_new.In the layer of buildings i need to move parcel number ("n_parc" field).If there is an intersection with the layer 'parcels_old' the buildings need their number, if there is an intersection with 'parcels_new' the buildings need their number, if there is an intersection with both layers, the number from the layer 'parcels_new' is needed . enter image description here

  • I suggest running the `intersection´ tool twice and then using the field calculator to keep the parcel numbers as you wish to.
    – Erik
    Feb 13, 2023 at 15:12
  • @Erik Thank you! I did, but I wanted to automate this field for new objects.
    – Ivan M
    Feb 14, 2023 at 7:04

1 Answer 1


You can use a simple if condition to check whether there is a value for the new parcels. If not take the value of the old parcels. If there are values for the new parcels, take those.

  • Thank you! Great solution!
    – Ivan M
    Feb 14, 2023 at 7:10

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