Am 6. Dezember 2017 18:42:22 MEZ schrieb Peter Tittmann <[email protected]>: >Thank you, Moritz. > >I'm pretty familiar with SQL but can’t figure out how layer 2 is stored >in the database. When I `pragma table_info(<vector>)` I only see the >layer 1 attributes.
v.db.connect -p (or grass.script.vector_db() )will show you all connections between the map and database tables. Moritz > >I’ll work with the GRASS approach you suggested. > >Best, >Peter > > >> On Dec 1, 2017, at 11:53 PM, Moritz Lennert ><[email protected]> wrote: >> >> On 02/12/17 02:03, Peter Tittmann wrote: >>> Hi, >>> I have a vector (`POINT`) which has two layers containing relevant >attributes (’strata’ and ’stand’). I would like to concatenate the two >values into a new attribute for Layer 1 (’<STRATA>_<STAND>’). I’ve been >struggling to sort this out for too long and am tapping out. Its >probably blatantly obvious but it has escaped me. >> >> >> Probably the easiest way if your not very familiar with SQL: >> >> - Create a new column in layer 1 where you can put the info from >layer 2 >> - Fill this column with v.to.db option=query query_layer=2, etc >> - Create a second new column to hold the concatenation >> - v.db.update to update this new column with the concatenation of the >two others (something like qcol = "STRATA || '_' || STAND") >> >> Otherwise, if there is a common key in both tables, you can just >create a new column and use db.execute to launch a UPDATE TABLE >directly, grabbing the info from the two table and concatenating it >directly in the query. >> >> Moritz >> >> >>> Thank you! >>> Here are some specifics. >>> east, north: 651849.842735, 6604949.78485 >>> c34_patch@project_area: >>> Type: Point >>> Id: 21622 >>> Layer: 1 >>> Category: 21623 >>> Driver: sqlite >>> Database: >/Users/pete/grassdata/PortGraham/project_area/sqlite/sqlite.db >>> Table: c34_patch >>> Key_column: cat >>> Attributes: >>> cat: 21623 >>> *strata: 3 — STRATA* >>> c34_patch@project_area: >>> Type: Point >>> Id: 21622 >>> Layer: 2 >>> *Category: 10 — STAND* >>> _______________________________________________ >>> grass-user mailing list >>> [email protected] <mailto:[email protected]> >>> https://lists.osgeo.org/mailman/listinfo/grass-user ><https://lists.osgeo.org/mailman/listinfo/grass-user> _______________________________________________ grass-user mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-user
