## 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, 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: Wednesday Nov 13 18:37:02 2024

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