[postgis-users] How to populate a column with results of isvalid

[Obe, Regina]

You wouldn't use that for tagging.  That is used if you want to prevent
people from adding invalid geometries into your table.  If you have
already got invalid geometries it will just fail since you have already
violated the rule you are trying to establish.

To add a field

ALTER TABLE mytable ADD COLUMN the_geom_is_valid boolean ;
UPDATE mytable SET the_geom_is_valid = ST_IsValid(the_geom);  //will
update existing

Unfortunately you can't put in a default value that references another
column which I think you may be looking for if you want to continually
add new data and have that field automatically fill.  For that you'll
need a (preferably BEFORE TRIGGER).

Hope that helps,
Regina

 

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Intengu Technologies
Sent: Wednesday, December 31, 2008 10:25 AM
To: PostGIS Users Discussion
Subject: [postgis-users] How to populate a column with results of
isvalid

I have loaded a polygon shapefile into postgis and would like to tag
each row with the results of st_isvalid in a new field. I found this
query in the postgis manual "ALTER TABLE mytable ADD CONSTRAINT
geometry_valid_check CHECK (isvalid((the_geom));" when I run the query
it picks an invalid geometry and stops

-- 
Sent from my mobile device

Sindile Bidla
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