I need to label some hydrants (points) - some of these belong to the fire brigade and have a number assigned to them, some do not and thus do not have a number. I would like to write an expression along the lines of:
'Label Hydrant with number if number exists, if hydrant has null value label with 'WO'.'
I just can't figure it out.
The simplest way for me to do this would be to change the null values to WO but the data is not mine, and I do not want to make changes to it. I suppose I could make a copy and put the values in the copy, but ideally I would like an expression.