James, There a couple of SQL plugins for QGIS. They allow you to visualize spatial features via 'ad hoc' queries (not whole tables).
I am pretty sure that I used the RT_SQL plugin. Here is a link to some info: http://underdark.wordpress.com/2010/10/16/visualizing-postgis-queries-in-qgis-using-rt-sql-layer-plugin/ No need to buy a $10,000 proprietary desktop GIS... David. On Wed, Jun 15, 2011 at 1:33 PM, James David Smith <james.david.sm...@gmail.com> wrote: > Dear Cristian & David, > > Thanks alot for your responses. > > Cristian - I don't have money to buy additional software > unfortunately. With regard to 'view' I actually don't know what this > is. I'm a bit of a beginner. I wonder if I made a 'view' whether I > could then query that view with QGIS. Something for me to look into... > > David - That looks like a good idea... but when adding data to QGIS > you can only select the whole table (I think) and then you manually > enter the 'WHERE' clause in a dialog box. I guess I could run the > query you suggest in PostgreSQL and save it into another table... and > then link QGIS to the new table. Though it all starts to get a bit > convoluted if I have to do that every time I want to look at some data > in QGIS... > > Cheers > > James > > > > On 15 June 2011 19:16, David Fawcett <david.fawc...@gmail.com> wrote: >> This is what is really cool about using a database to store your data... >> >> Change your query to: >> >> SELECT mycol1, >> mycol2, >> date_time_of_arrival as dt_arrive, >> date_time_of_departure as dt_depart, >> the_geom >> FROM incidents >> WHERE urgency = 'Immediate' >> AND date_time_of_arrival - date_time_unit_assigned > '00:12:00' >> >> Note: you will need to specify the names of the columns that you are >> interested in. >> >> >> On Wed, Jun 15, 2011 at 12:58 PM, James David Smith >> <james.david.sm...@gmail.com> wrote: >>> Dear all, >>> >>> I appreciate that this is more of a QGIS query, but I think that the >>> route of the problem might be in PostGIS, so... I have opened QGIS and >>> ran the query on my PostGIS table as below: >>> >>> SELECT * FROM incidents >>> WHERE urgency = 'Immediate' >>> AND date_time_of_arrival - date_time_unit_assigned > '00:12:00' >>> >>> This gives me 33 points in QGIS. Great. I would now however like to >>> save this as a ShapeFile for use in ArcGIS with which I am more >>> familiar, but when I try to SAVE AS from QGIS I am given the following >>> error.... >>> >>> Export to vector file failed. >>> Error: trimming attribute name 'date_time_of_arrival' to ten >>> significant characters produces duplicate column name. >>> >>> I am guessing that the problem here is that ESRI shapefiles can only >>> deal with column names that are ten characters long...? And that as I >>> also have a column called 'date_time_of_departure', when QGIS trims >>> this column it ends up with two columns called the same thing? Is >>> there a way around this? I realise I could rename the column in QGIS, >>> but I actually have around 45 columns in the table and this problem >>> will occur with about 15 pairs of them I think. I guess there is no >>> simple answer... but thought I'd ask. >>> >>> Cheers >>> >>> James >>> _______________________________________________ >>> postgis-users mailing list >>> postgis-users@postgis.refractions.net >>> http://postgis.refractions.net/mailman/listinfo/postgis-users >>> >> _______________________________________________ >> postgis-users mailing list >> postgis-users@postgis.refractions.net >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users