[Qgis-user] CSV layer, Time column null expressie to test for NULL/empty?

[Raymond Nijssen]

Or:

coalesce(field, '') in ('', ' ', 'NULL')

Raymond


On 19-01-2023 09:53, kirk via QGIS-User wrote:
> You can also use
> CASE
> When field is null then 123
> else 321
> end
> 
> Kirk Schmidt
> 
> 
> 
> Sent from my Galaxy
> 
> 
> -------- Original message --------
> From: Richard Duivenvoorde via QGIS-User <qgis-user at lists.osgeo.org>
> Date: 2023-01-18 1:44 p.m. (GMT-04:00)
> To: qgis-user at lists.osgeo.org
> Subject: Re: [Qgis-user] CSV layer, Time column null expressie to test 
> for NULL/empty?
> 
> 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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