db.select.1grass man page

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

Keywords

database, attribute table, SQL

Synopsis

db.select
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]

Flags

-c
Do not include column names in output
-d
Describe query only (don’t run it)
-v
Vertical output (instead of horizontal)
-t
Only test query, do not execute
--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

sql=sql_query
SQL select statement
For example: ’select * from rybniky where kapri = ’hodne’
input=name
Name of file containing SQL select statement(s)
’-’ for standard input
table=name
Name of table to query
driver=name
Name of database driver
Options: mesql, pg, dbf, sqlite, odbc, ogr, mysql
Default: sqlite
database=name
Name of database
Default: $GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db
separator=character
Field separator
Special characters: pipe, comma, space, tab, newline
Default: pipe
vertical_separator=character
Vertical record separator (requires -v flag)
Special characters: pipe, comma, space, tab, newline
null_value=string
String representing NULL value
output=name
Name for output file (if omitted or "-" output to stdout)

Description

db.select prints result of selection from database based on SQL statement read from input file or from standard input to standard output.

Note

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).

Examples

Basic usage

db.select sql="select * from roads"

or

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

or

db.select input=file.sql

or

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

Authors

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: 2014-11-28 10:58:18 +0100 (Fri, 28 Nov 2014) $

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