db.select(1grass)

NAME
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
    Example: select * from towns where population > 10000

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: dbf, mysql, odbc, ogr, pg, sqlite
    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. Each individual query has to be written on one single line and different queries have to be written on separate lines.

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

SOURCE CODE

Available at: db.select source code (history)

Accessed: Friday Apr 04 01:18:43 2025

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© 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual