db.select.1grass man page

db.select — Selects data from attribute table.
Performs SQL query statement(s).


database, attribute table, SQL


db.select --help
db.select [-cdvt]  [sql=sql_query]   [input=name]   [table=name]   [driver=name]   [database=name]   [separator=character]   [vertical_separator=character]   [null_value=string]   [output=name]   [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]



Do not include column names in output


Describe query only (don’t run it)


Vertical output (instead of horizontal)


Only test query, do not execute


Allow output files to overwrite existing files


Print usage summary


Verbose module output


Quiet module output


Force launching GUI dialog



SQL SELECT statement
Example: select * from towns where population > 10000


Name of file containing SQL select statement(s)
’-’ for standard input


Name of table to query


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


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


Field separator
Special characters: pipe, comma, space, tab, newline
Default: pipe


Vertical record separator (requires -v flag)
Special characters: pipe, comma, space, tab, newline


String representing NULL value


Name for output file (if omitted or "-" output to stdout)


db.select prints result of selection from database based on SQL statement read from input file or from standard input to standard output. Each individual query has to be written on one single line and different queries have to be written on separate lines.


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. Output will be displayed to standard output or can be directed to a file (option output).


Basic usage

db.select sql="select * from roads"


echo "select * from roads" | db.select input=-


db.select input=file.sql


cat file.sql | db.select input=-

Select all from table roads:

db.select -c driver=odbc database=mydb table=hospitals \
          input=file.sql output=result.csv

Select some string attribute, exclude others:

db.select sql="SELECT * FROM archsites WHERE str1 <> ’No Name’"

Select some string attribute with ZERO length:

db.select sql="SELECT * FROM archsites WHERE str1 IS NULL"

Select coordinates from PostGIS table:

db.select sql="SELECT x(geo),y(geo) FROM localizzazione"

Execute multiple SQL statements

cat file.sql
SELECT * FROM busstopsall WHERE cat = 1
SELECT cat FROM busstopsall WHERE cat > 4 AND cat < 8
db.select input=file.sql

Count number of cases falling into same position

When multiple observation have the spatial coordinates, they can still be counted (if needed, coordinates can be uploaded to the attribute table by v.to.db:

db.select sql="SELECT long,lat,site_id,department,obs,COUNT(long) as count_cases \
               FROM diseases GROUP BY long,lat"

See Also

db.connect, db.describe, db.drivers, db.droptable, db.execute, db.login, db.tables

GRASS SQL interface


Original author unknown (probably CERL)
Modifications by Radim Blazek, ITC-Irst, Trento, Italy
Support for multiple statements by Martin Landa, Czech Technical University in Prague

Last changed: $Date$

Source Code

Available at: db.select source code (history)

Main index | Database index | Topics index | Keywords index | Graphical index | Full index

© 2003-2019 GRASS Development Team, GRASS GIS 7.8.1 Reference Manual


GRASS 7.8.1 Grass User's Manual