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v.db.update
Langue: en
Version: 370629 (fedora - 01/12/10)
Section: 1 (Commandes utilisateur)
NAME
v.db.update - Allows to update a column in the attribute table connected to a vector map.KEYWORDS
vector, database, attribute tableSYNOPSIS
v.db.updatev.db.update help
v.db.update map=string [layer=integer] column=string [value=string] [qcolumn=string] [where=string] [--verbose] [--quiet]
Parameters:
- map=string
Vector map to edit the attribute table for- layer=integer
Layer to which the table to be changed is connected
Default: 1- column=string
Column to update- value=string
Value to update the column with (varchar values have to be in single quotes, e.g. 'grass')- qcolumn=string
Column to query- where=string
WHERE conditions for update, without 'where' keyword (e.g. cat=1 or col1/col2>1)
DESCRIPTION
v.db.update allows to assign a new value to a column in the attribute table connected to a given map. Alternatively, values can be copied from another column in the table.NOTES
v.db.update is just a front-end to db.execute to allow easier usage. For complex SQL UPDATE statements, db.execute should be used.EXAMPLES
Spearfish: adding new column, inserting selectively a specified value:g.copy vect=fields,myfields
v.db.addcol myfields col="polynum integer"
v.db.update myfields col=polynum val=42 where="label='V. White#1'"
v.db.select myfields
Spearfish: adding new column, copying values from other table column with on the fly calculation:
g.copy vect=fields,myfields
v.db.addcol myfields col="polynum integer"
v.db.update myfields col=polynum qcol="cat*2"
v.db.select myfields
Type cast (type conversion) of strings to double precision (unsupported by DBF driver):
v.db.update mygeodetic_pts col=zval qcol="CAST(z_value AS double precision)" rs
where="z_value <> 'N/A'"
SEE ALSO
db.execute, v.db.addcol, v.db.addtable, v.db.connect, v.db.droptable, v.db.join, v.db.selectGRASS SQL interface
AUTHOR
Moritz Lennert (mlennert@club.worldonline.be)Last changed: $Date: 2007-06-29 09:51:12 +0200 (Fri, 29 Jun 2007) $
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