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, 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)
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).
db.select sql="select * from roads"
or
echo "select * from roads" | db.select input=-
or
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"
cat file.sql
SELECT * FROM busstopsall WHERE cat = 1
SELECT cat FROM busstopsall WHERE cat > 4 AND cat < 8
db.select input=file.sql
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"
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
SOURCE CODE
Available at:
db.select source code
(history)
Latest change: Wednesday Nov 27 22:53:26 2024 in commit: 3b5486c0463a7103ab2109e28bf860fe34539868
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GRASS Development Team,
GRASS GIS 8.5.0dev Reference Manual