NAME¶
v.db.connect - Prints/sets DB connection for a vector map to
attribute table.
KEYWORDS¶
vector, database, attribute table
SYNOPSIS¶
v.db.connect
v.db.connect help
v.db.connect [-
pglcod]
map=
name
[
driver=
name] [
database=
name]
[
table=
name] [
key=
name]
[
layer=
integer] [
fs=
character] [--
verbose]
[--
quiet]
Flags:¶
- -p
-
Print all map connection parameters and exit
- -g
-
Print all map connection parameters and exit in shell script style
Format: layer[/layer name] table key database driver
- -l
-
When printing, limit to layer specified by the layer option
- -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)
- --verbose
-
Verbose module output
- --quiet
-
Quiet module output
Parameters:¶
- map=name
-
Name of input vector map
- driver=name
-
Driver name
Options: pg,dbf,ogr,odbc,mysql,sqlite
Default: dbf
- database=name
-
Database name
Default: $GISDBASE/$LOCATION_NAME/$MAPSET/dbf/
- table=name
-
Table name
- key=name
-
Key column name
Must refer to an integer column
Default: cat
- layer=integer
-
Layer number
A single vector map can be connected to multiple database tables. This
number determines which table to use.
Default: 1
- fs=character
-
Field separator
Field separator for shell script style output
Default:
DESCRIPTION¶
v.db.connect prints or sets database connection for a vector map. The
user can add or remove link to attribute table on the certain layer.
NOTE¶
If parameters for database connection are already set with db.connect, they are
taken as default values and do not need to be spcified each time.
When printing database connection (
p or
g flag) the parameter
layer is ignored, i.e.
all connections are printed to the
output, unless
l flag is given.
Attention: Removing a vector map will also delete all tables linked to
it! If you use v.db.connect to link further tables to your map, it is
advisable to make a copy from those tables first and connect the copied tables
to the vector map (see also v.overlay).
EXAMPLE¶
Print database connection¶
Print all database connection parameters for vector map.
v.db.connect -p map=roads
Print column types and names of table linked to vector map.
v.db.connect -c map=roads
Connect vector map to database (DBF driver)¶
Connect vector map to DBF table without or with variables.
Using default DB connection:
v.db.connect map=vectormap table=table
Using hardcoded path to DBF directory (not recommended):
v.db.connect map=vectormap table=table \
database=/home/user/grassdata/spearfish60/PERMANENT/dbf
Using variable as DBF directory definition, single quotes must be used:
v.db.connect map=vectormap table=table \
database='$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/$MAPSET/sqlite.db'
db.tables -p
v.db.connect map=vectormap table=table driver=sqlite \
database='$GISDBASE/$LOCATION_NAME/$MAPSET/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 illustrated a mixed data storage with possibility top update
attributes in 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.
SEE ALSO¶
db.connect, db.copy, db.tables,
v.db.addtable, v.db.droptable, v.db.addcol,
v.db.dropcol, v.external, v.in.db, v.overlay
AUTHOR¶
Radim Blazek, ITC-Irst, Trento, Italy
Last changed: $Date: 2011-11-08 12:29:50 +0100 (Tue, 08 Nov 2011) $
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