"NULL" means unknown, so you can't say if another value = NULL, it may or may
not - the db can't tell.
Instead of "=" there is usually an "isnull" or "is null" operator in your
database to test for null,
in your case, try:update "mc-roadsegs" Set "RFROMHN" = "" Where "RFROMHN" is
null;
(I use Postgis rather than Spatialite, which would use ' instead of " to define
strings, so:update "mc-roadsegs" Set "RFROMHN" = '' Where "RFROMHN" is null;)
HTH,
Brent Wood
From: Chuck Young <[email protected]>
To: [email protected]
Sent: Sunday, March 15, 2015 10:57 AM
Subject: [Qgis-user] SQL to update table
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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