Hi!
Another suggestion would be to use two tables. One for "latest" known position and one for "historical" position. When you receive vehicle information, you update the "latest" table (or insert if it is the first entry for a given vehicle) and you insert into the "historical" one. Thus, if you want to display the current vehicle position, you don't have to bother about filtering, you have all what you need, one row per vehicle, in the "latest" table. On the other hand, when you want to playback a vehicle route for let's say the previous day, you can use the "historical" table. Pierre ________________________________ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Kenneth Skovhede, GEOGRAF A/S Sent: June 17, 2008 05:59 To: MapGuide Users Mail List Subject: Re: [mapguide-users] Vehicle Tracking So you want to display only the most recent vehicle positions? You can do that with a filter on the layer. I suspect you have a datastructure like: x double y double vehicleid integer timestamp datetime You should have a filter like: "timestamp = (select top 1 timestamp from table where vehicleid = id)". How this filter should look, depends on your database. I suspect you will have a hard time figuring this out (if it is even possible) directly in MapGuide. I would advise you to add a column that indicates that this is the most recent entry: mostrecent integer then you can update the database upon arival of requests: update table set mostrecent = 0 where vehicleid=id and insert insert into table (x,y,vehicleid,timestamp,mostrecent) values (x,y,id,now(),1) This will allow you to have a filter like this in your layer: "mostrecent = 1" Regards, Kenneth Skovhede, GEOGRAF A/S Vishaal skrev: Hi Kenneth, i am successful in displaying the points on a button click all at once. what i want is that on the button click my points should get displayed one by one as per the data and only the latest point should be visible. i am not able to this part. can you help me with some code example? thanks. Kenneth Skovhede, GEOGRAF A/S wrote: If you only have to consider the current position of vehicles, you can easily use a database. Just add an x,y columns, and perhaps speed and other data to a table. Then make a service that accepts coordinates from vehicles, and update the correct row in the database. In MapGuide, make a layer that reads the x,y points, and perhaps color code according to speed. You can then get away with refreshing the map periodically. If you can read in the direction, you could throw in a rotation on a symbol in the layer. Regards, Kenneth Skovhede, GEOGRAF A/S Vishaal skrev: Hi List, i want to develop a vehicle tracking system using MGOS 1.2 and Visual Studio 2005. if any one can guide me about how to start for the application, then it will be very helpful to me. thanks for all your support. _______________________________________________ mapguide-users mailing list mapguide-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapguide-users
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