Pff, ok found a solution:
"bezoek.begintijd" IS NULL
works
So if I want to test for empty strings, or NULL (like strings), AND real NULLS,
I use now:
( "bezoek.begintijd" IS NULL OR "bezoek.begintijd" in ('', ' ', 'NULL') )
Regards,
Richard Duivenvoorde
On 1/18/23 18:31, Richard Duivenvoorde via QGIS-User wrote:
We have csv data, which is loaded as layer via the Delimited Text Layer
provider.
The data contains both a date and a time column, which we have to format as
isodatetime using an QGIS Expression.
BUT sometimes time column is empty/no value (in which case we have to format it
as isoTIME only).
So we have to check IF the time column is empty, then only format the Date,
else use Date AND Time.
My problem is that I fail to create an expression for the test IF the column
(see screenshot) is empty.
I thought to use (our column is called "bezoek.begintijd"):
"bezoek.begintijd" in ('', ' ', NULL)
BUT this does NOT return True or False, but NULL !!
But:
("bezoek.begintijd" in ('', ' ', NULL)) = NULL
does ALSO NOT resolve to True... (also NULL)
When the record has no data (the csv holds no data for that record), it shows
<time: >
if it has data:
<time: 09:42:00>
Anybody an idea what test I can use to test if the time column (which is typed
as Time) is empty/null/none?
Thanks for any pointers.
Regards,
Richard Duivenvoorde
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