On Sun, Mar 15, 2015 at 11:49 PM, Rich Shepard <rshep...@appl-ecosys.com> wrote:
> On Sun, 15 Mar 2015, Andy Wickert wrote: > > So to boil it down to the simplest part of what you said, the key is just >> to have an ID column in the GRASS table that links to a table in a >> database structure outside of GRASS? >> > > Andy, > > Yes. You can keep all point attributes in SQLite (or other rdbms) tables > rather than in GRASS. It's been a while since I last did this so the > specifics are not immediately available. I would link each point to a table > which describes it; perhaps including geographic coordinates, name, and > other information. Then your discharge and sediment data are in other > tables > that are related to each row in the main table. This also allows you to run > SQL queries on the data (such as descriptice statistics) outside of GRASS. > > Just to make sure that I was clear: the problem is how to include multiple >> rows of data that all correspond to just one point in GIS (so "grain size" >> with frequencies in each grain size class or "discharge" with discharges >> at different times). >> > > Database design is a topic of itself. Separate attribute data from the > spatial data; the former goes into a database (multiple tables), the latter > in GRASS files. > > In your initial message you describe three different categories of data > and each should be in its own table. Information about each data collection > point (which is seen on the map) is in one table. This could include a site > ID as the primary key, site name, perhaps the stream or drainage basin in > which it is located, and other information about the location itself. > > Your second table contains hydaulic data: sample ID (the primary key), > station ID (which relates that row to your point), collection date and > time, > discharge, channel width, and any other relevant information. > > Your third table contains sediment data: sample ID (primary key), station > ID, date and time, each grain category (e.g., silt, clay, fine sand, coarse > sand, gravel, cobble), and the percentage or proportion (dry weight?) of > each. > > You could also have additional tables if you want to store more > categories > of data for each point. > > Hope this helps, > > Rich > > > > > _______________________________________________ > grass-user mailing list > grass-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-user > Hi Rich, This helps very much and learning how to do this will be high on my to-do list. Thank you! Andy
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