v.db.select(1grass) GRASS GIS User's Manual v.db.select(1grass)
NAME
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] [col-
umns=name[,name,...]] [where=sql_query] [group=string] [separa-
tor=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 ac-
cess 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 population >= 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)
SOURCE CODE
Available at: v.db.select source code (history)
Accessed: unknown
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