Rich Shepard <rshep...@appl-ecosys.com> schreef op 15 maart 2015 23:49:06 CET: >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.
The attribute table is in a sqlite table already, unless you are still using dbf as database backend for grass. Just link your other tables to that attribute table? 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 -- Sent from my Android device with K-9 Mail. Please excuse my brevity. _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user