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, 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

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)

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)

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

# 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.

Store geometry in GRASS but attributes in PostGIS

# 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.