[Qgis-user] SQL to update table

[Bo Victor Thomsen]

You might try:

update "mc-roadsegs" Set "RFROMHN" = "" Where "RFROMHN" IS NULL;

NULL signify the absence of a value in a field; it not a specific value; 
therefore you can't use the "=" operator (as in "RFROMHN" = "NULL")

Regards
Bo Victor Thomsen
AestasGIS
Denmark

Den 14-03-2015 kl. 22:57 skrev Chuck Young:
> I am trying to eliminate the text "NULL" from a table.  I have 
> imported a set of Tiger road data and in some of the columns that I 
> need to display the data itr has "NULL" in the field.  If it is Null I 
> would really like that NOT to show up in the labeling on the map.
>
> I have tried some standard SQL update queries but they didn't work.
>
> I tried the following from the QSpatialite form that appears from 
> within QGIS.
> Example:
> update "mc-roadsegs" Set "RFROMHN" = "" Where "RFROMHN" = "NULL";
>
> I also tried to construct a query from within the query builf=der at 
> the top of the Attribute table in Edit mode.
>
> I really need to remove these unwanted valued.  It has been a while 
> since I used SQL on a routine basis so I am a bit rusty.
>
> Any help will be much appreciated!
>
> Thanks
>
> Chuck
>
>
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