NAME

       v.db.connect  - Prints/sets DB connection for a vector map to attribute table.

KEYWORDS

       vector, attribute table, database, layer

SYNOPSIS

       v.db.connect
       v.db.connect --help
       v.db.connect    [-pgcod]    map=name    [driver=name]     [database=name]     [table=name]
       [key=name]   [layer=string]   [separator=character]   [--overwrite]  [--help]  [--verbose]
       [--quiet]  [--ui]

   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: mysql, odbc, sqlite, pg, ogr, dbf
           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

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

       Connection information (driver, database, table, key) is stored for each map, in the file
       <database>/<location>/<mapset>/vector/<map>/dbln

       If parameters for database connection are already set with db.connect, they are  taken  as
       default values and do not need to be specified each time.

       When  printing  database connection (p or g flag) the parameter layer is ignored, i.e. all
       connections are printed to the output.

       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

       Note: The default database backend setting is SQLite.

   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  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.addcolumn,
       v.db.dropcolumn, v.external, v.in.db, v.overlay

AUTHOR

       Radim Blazek, ITC-Irst, Trento, Italy

       Last changed: $Date: 2015-10-01 23:15:07 +0200 (Thu, 01 Oct 2015) $

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       © 2003-2016 GRASS Development Team, GRASS GIS 7.0.3 Reference Manual