table of contents
db.select(1grass) | GRASS GIS User's Manual | 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: Thursday Aug 01 05:15:58 2024
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