Flags:¶

-p

Print all map connection parameters and exit

-g

Print all map connection parameters in shell script style and exit
Format: layer[/layer name] table key database driver

-c

Print types/names of table columns for specified layer and exit

-o

Overwrite connection parameter for certain layer

-d

Delete connection for certain layer (not the table)

--overwrite

Allow output files to overwrite existing files

--help

Print usage summary

--verbose

Verbose module output

--quiet

Quiet module output

--ui

Force launching GUI dialog

Parameters:¶

map=name [required]

Name of vector map
Or data source for direct OGR access

driver=name

Name of database driver
Options: dbf, mysql, odbc, ogr, pg, sqlite
Default: sqlite

database=name

Name of database
Default: $GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db

table=name

Name of attribute table

key=name

Name of key column
Must refer to an integer column
Default: cat

layer=string

Layer number or name
Format: layer number[/layer name]
Default: 1

separator=character

Field separator for shell script style output
Special characters: pipe, comma, space, tab, newline
Default: pipe

Print database connection¶

Print all database connection parameters for vector map.

v.db.connect -p map=roads

Print column types and names of table linked to vector map.

v.db.connect -c map=roads

Connect vector map to database (DBF driver)¶

Connect vector map to DBF table without or with variables.

Using default DB connection:

v.db.connect map=vectormap table=table

Using hardcoded path to DBF directory (not recommended):

v.db.connect map=vectormap table=table \


             database=/home/user/grassdata/spearfish60/PERMANENT/dbf

Using variable as DBF directory definition, single quotes must be used:

v.db.connect map=vectormap table=table \


             database=’$GISDBASE/$LOCATION_NAME/$MAPSET/dbf/’

Connect vector map layer 2 and key ID to database with variables (note: if needed, single quotes must be used for the database parameter):

v.db.connect map=vectormap table=table layer=2 key=ID

Connect vector map to database (SQLite driver)¶

Very similar to DBF driver example above.

db.connect driver=sqlite database=’$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db’
db.tables -p
v.db.connect map=vectormap table=table driver=sqlite \


             database=’$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db’
v.db.connect -p map=vectormap

Connect vector map to database (MySQL driver)¶

# note: connection which requires password
db.connect driver=mysql database="host=dbserver.foo.org,dbname=my_database"
db.login user=joshua [password=xxx]
# ... or enter password interactively.
db.tables -p
# connect external table to layer 2:
v.db.connect map=my_map table=my_mysql_table key=baz layer=2
v.db.connect -p my_map

Connect vector map to database (PostgreSQL driver)¶

# note: connection without password being asked
v.db.connect map=vectormap table=table layer=1 key=oid driver=pg \


             database="host=myserver.itc.it,dbname=mydb,user=name" \


             table=mytable key=id

Store geometry in GRASS but attributes in PostgreSQL¶

This example illustrates a mixed data storage with possibility to update attributes in an external PostgreSQL database:

# Check current settings for attribute storage:
db.connect -p
# Import table from PostgreSQL to new map
# (NOTE: output map name needs to be different from table name in
#        case that GRASS is connected to PostgreSQL):
v.in.db driver=pg database="host=localhost,dbname=meteo" \


        table=mytable x=lon y=lat key=cat out=mytable
v.db.connect map=mytable -p
# Cancel table connection between map and attribute table:
v.db.connect map=mytable -d
v.db.connect map=mytable -p
# Drop table which was replicated due to import:
db.tables -p
echo "DROP TABLE mytable" | db.execute
db.tables -p
# reconnect map to table in PostgreSQL:
v.db.connect map=mytable driver=pg database="host=localhost,dbname=meteo" \


        table=mytable key=cat
# Now the geometry is stored in GRASS while the attributes are stored
# in PostgreSQL.

An alternative is to create a "view" of only ID, x, y [,z] columns and to use v.in.db on this view, then connect the original table to the geometry. This will be faster if the original table is very large.

Store geometry in GRASS but attributes in PostGIS¶

This example illustrated a mixed data storage with possibility top update attributes in external PostGIS database:

# Check current settings for attribute storage:
db.connect -p
# Import table from PostGIS to new map
# (NOTE: output map name needs to be different from table name in
#        case that GRASS is connected to PostGIS):
v.in.db driver=pg database="host=localhost,dbname=meteo" \


        table=mytable x="x(geom)" y="y(geom)" key=cat out=mytable
v.db.connect map=mytable -p
# Cancel table connection between map and attribute table:
v.db.connect map=mytable -d
v.db.connect map=mytable -p
# Drop table which was replicated due to import:
db.tables -p
echo "DROP TABLE mytable" | db.execute
db.tables -p
# reconnect map to table in PostGIS:
v.db.connect map=mytable driver=pg database="host=localhost,dbname=meteo" \


        table=mytable key=cat
# Now the geometry is stored in GRASS while the attributes are stored
# in PostGIS.