NAME

       v.db.join  - Joins a database table to a vector map table.

KEYWORDS

       vector, attribute table, database

SYNOPSIS

       v.db.join
       v.db.join --help
       v.db.join   map=name    [layer=string]    column=name  other_table=name  other_column=name
       [subset_columns=name[,name,...]]   [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       --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
           Vector map to which to join other table

       layer=string
           Layer number or name
           Layer where to join
           Default: 1

       column=name [required]
           Identifier column (e.g.: cat) in the vector table to be used for join

       other_table=name [required]
           Other table name

       other_column=name [required]
           Identifier column (e.g.: id) in the other table used for join

       subset_columns=name[,name,...]
           Subset of columns from the other table

DESCRIPTION

       v.db.join joins the content of another table into  the  connected  attribute  table  of  a
       vector map.

NOTES

       v.db.join  is a front-end to db.execute to allow easier usage.  The vector attribute table
       must be stored in a SQL database (SQLite, PostgreSQL, MySQL, ODBC, ...). The  DBF  backend
       is not supported. Tables can be imported with db.in.ogr.

       The vector map-database connection(s) can be verified with v.db.connect.

EXAMPLES

       Exercise  to  join North Carolina geological classes from a CSV table to the "geology" map
       of the North Carolina sample dataset (requires download of legend CSV file  nc_geology.csv
       from External data for NC sample dataset):
       # check original map attributes
       v.db.select geology column=GEO_NAME,SHAPE_area
       # import of CSV table
       db.in.ogr input=nc_geology.csv output=nc_geology
       # work on copy of geology map in current mapset
       g.copy vector=geology,mygeology
       # check column names of vector map attributes
       v.info -c mygeology
       # check column names of legend table
       db.describe -c nc_geology
       # join table using key columns (map: "GEO_NAME"; table: "geol_id")
       v.db.join map=mygeology column=GEO_NAME other_table=nc_geology other_column=geol_id
       # verify result (here abbreviated)
       v.db.select mygeology | head -3
       cat|onemap_pro|PERIMETER|GEOL250_|GEOL250_ID|GEO_NAME|SHAPE_area|SHAPE_len|geol_id|longname|comment
       1|963738.75|4083.97998|2|1|Zml|963738.608571|4083.979839|Zml|Metagraywacke|Interlayered with metaconglomerate, ...
       2|22189124|26628.261719|3|2|Zmf|22189123.2296|26628.261112|Zmf|Metafelsite|Light-colored porphyritic extrusive rock
       ...

   Soil map table join
       Joining  the  soil  type explanations from table soils_legend into the Spearfish soils map
       (download legend):
       g.copy vect=soils,mysoils
       # import legend table
       db.in.ogr soils_legend.csv out=soils_legend
       # get join column names
       v.info -c mysoils
       db.describe -c soils_legend
       # look at original table
       v.db.select mysoils
       cat|label
       1|Aab
       2|Ba
       3|Bb
       4|BcB
       5|BcC
       ...
       # look at legend
       db.select table=soils_legend
       db.select table=soils_legend | head -7
       id|shortname|longname
       0|no data|no data
       0|AaB|Alice fine sandy loam, 0 to 6
       0|Ba|Barnum silt loam
       0|Bb|Barnum silt loam, channeled
       0|BcB|Boneek silt loam, 2 to 6
       0|BcC|Boneek silt loam, 6 to 9
       ...
       # join soils_legend into mysoils attribute table
       v.db.join mysoils col=label other_table=soils_legend ocol=shortname
       # verification of join
       v.db.select mysoils
       cat|label|id|shortname|longname
       1|Aab|||
       2|Ba|2|Ba|Barnum silt loam
       3|Bb|3|Bb|Barnum silt loam, channeled
       4|BcB|4|BcB|Boneek silt loam, 2 to 6
       5|BcC|5|BcC|Boneek silt loam, 6 to 9
       ...

SEE ALSO

        db.execute, db.in.ogr, db.select, v.db.update
       GRASS SQL interface

AUTHOR

       Markus Neteler

SOURCE CODE

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

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual