v.db.select.1grass man page

v.db.select — Prints vector map attributes.

Keywords

vector, attribute table, database, SQL

Synopsis

v.db.select
v.db.select --help
v.db.select [-rcvf] map=name  [layer=string]   [columns=name[,name,...]]   [where=sql_query]   [group=string]   [separator=character]   [vertical_separator=character]   [null_value=string]   [file=name]   [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]

Flags

-r

Print minimal region extent of selected vector features instead of attributes

-c

Do not include column names in output

-v

Vertical output (instead of horizontal)

-f

Exclude attributes not linked to features

--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

map=name [required]

Name of vector map
Or data source for direct OGR access

layer=string

Layer number or name
Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
Default: 1

columns=name[,name,...]

Name of attribute column(s)

where=sql_query

WHERE conditions of SQL statement without ’where’ keyword
Example: income < 1000 and inhab >= 10000

group=string

GROUP BY conditions of SQL statement without ’group by’ keyword

separator=character

Field separator
Special characters: pipe, comma, space, tab, newline
Default: pipe

vertical_separator=character

Output vertical record separator
Special characters: pipe, comma, space, tab, newline

null_value=string

String representing NULL value

file=name

Name for output file (if omitted or "-" output to stdout)

Description

v.db.select prints attributes of a vector map from one or several user selected attribute table columns.

Examples

All examples are based on the North Carolina sample dataset.

Select and show entire table

v.db.select map=roadsmajor
cat|MAJORRDS_|ROAD_NAME|MULTILANE|PROPYEAR|OBJECTID|SHAPE_LEN
1|1|NC-50|no|0|1|4825.369405
2|2|NC-50|no|0|2|14392.589058
3|3|NC-98|no|0|3|3212.981242
4|4|NC-50|no|0|4|13391.907552
...

Select and show single column from table

Note: multiple columns can be specified as comma separated list.

v.db.select map=roadsmajor column=ROAD_NAME
NC-50
NC-50
NC-98
NC-50
NC-98
...

Print region extent of selected vector features

v.db.select -r map=roadsmajor where="ROAD_NAME = ’NC-98’"
n=248425.389891
s=245640.640081
w=635906.517653
e=661979.801880

Select empty vector features (no data entries)

v.db.select geonames_wake where="ALTERNATEN IS NULL"
cat|GEONAMEID|NAME|ASCIINAME|ALTERNATEN|FEATURECLA|FEATURECOD|...
8|4498303|West Raleigh|West Raleigh||P|PPL|US||NC|338759|123|...
14|4459467|Cary|Cary||P|PPL|US||NC|103945|146|152|America/Iqaluit|...
31|4452808|Apex|Apex||P|PPL|US||NC|30873|167|134|America/Iqaluit|...
...

Select not empty vector features (no data entries)

v.db.select geonames_wake where="ALTERNATEN IS NOT NULL"
cat|GEONAMEID|NAME|ASCIINAME|ALTERNATEN|FEATURECLA|FEATURECOD|...
9|4487042|Raleigh|Raleigh|Raleigh,...
31299|4487056|Raleigh-Durham Airport|Raleigh-Durham Airport|...
...

Select features with distinct road names

v.db.select map=roadsmajor columns=ROAD_NAME group=ROAD_NAME
ROAD_NAME
I-40
I-440
I-540
NC-231
NC-39
NC-42
...

It is also possible to combine with where option

v.db.select map=roadsmajor columns=ROAD_NAME,MULTILANE group=ROAD_NAME where=’ROAD_NAME is not null’
ROAD_NAME|MULTILANE
I-40|yes
I-440|yes
I-540|yes
NC-231|no
NC-39|no
NC-42|no
NC-50|no
NC-54|no
NC-55|no
NC-96|no
NC-97|no
NC-98|no
US-1|
US-401|no
US-64|yes
US-70|yes

It can also use more columns in group option

v.db.select map=roadsmajor columns=ROAD_NAME,MULTILANE group=ROAD_NAME,MULTILANE where=’ROAD_NAME is not null’
ROAD_NAME|MULTILANE
I-40|yes
I-440|yes
I-540|yes
NC-231|no
NC-39|no
NC-42|no
NC-50|no
NC-54|no
NC-55|no
NC-96|no
NC-97|no
NC-98|no
US-1|
US-1|yes
US-401|no
US-401|yes
US-64|yes
US-70|yes

See Also

db.select

Authors

Radim Blazek, ITC-Irst, Trento, Italy
Minimal region extent added by Martin Landa, FBK-irst (formerly ITC-irst), Trento, Italy (2008/08)
Group option added by Luca Delucchi, Fondazione Edmund Mach, Trento, Italy (2015/12)

Last changed: $Date: 2016-10-27 23:24:04 +0200 (Thu, 27 Oct 2016) $

Source Code

Available at: v.db.select source code (history)

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