Brilliant - now works - Many thanks Pierma!
From: Pierre-Marie Le Dantec [mailto:[email protected]] Sent: Thursday, 31 March 2016 7:17 AM To: Phil (The Geek) Wyatt Cc: [email protected] Subject: RE: [Qgis-user] Selecting records Do tou have an error or result is not as expected ? If qgis complains about sql query or invalid layer, it can be because i forgot fields calculated through a function need to be explicitly named: SELECT stationid, MAX(obs_date) AS max_date FROM your_layer GROUP BY stationid This should works on any valid layer. Tested successfully with a GeoJSON layer. Pierma Le 30 mars 2016 21:19, "Phil (The Geek) Wyatt" <[email protected]> a écrit : Alas, this doesn't seem to work on the GEOJSON linked layer From: Pierre-Marie Le Dantec [mailto:[email protected]] Sent: Wednesday, 30 March 2016 3:59 PM To: Phil (The Geek) Wyatt Cc: [email protected] Subject: Re: [Qgis-user] Selecting records Hi Phil, For manipulating dates throught SQL you should use ISO format ("YYYY-MM-DD"). Then, you can use a virtual layer with : SELECT stationid, MAX(obs_date) FROM your_layer GROUP BY stationid Cheers, Pierma 2016-03-30 13:09 GMT+11:00 Phil (The Geek) Wyatt <[email protected]>: I must be thick, but I can't get my head around this in QGIS Data stationid_ obs_date BK21 28/03/2016 BK21 29/03/2016 BK21 30/03/2016 BL22 28/03/2016 BL22 29/03/2016 BL22 30/03/2016 BL22 31/03/2016 How do I select the Maximum date for each station ID? The data will be coming from a GEOJSON feed but I can also pull it as a shape file if needs be Cheers - Phil _______________________________________________ Qgis-user mailing list [email protected] List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user -- Pierre-Marie Le Dantec 73.64.34
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