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)" \
            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.select
GRASS SQL interface

AUTHOR

Moritz Lennert (mlennert@club.worldonline.be)

Last changed: $Date$