1v.db.update(1) Grass User's Manual v.db.update(1)
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6 v.db.update - Allows to update a column in the attribute table con‐
7 nected to a vector map.
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10 vector, database, attribute table
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13 v.db.update
14 v.db.update help
15 v.db.update map=string [layer=integer] column=string [value=string]
16 [qcolumn=string] [where=string] [--verbose] [--quiet]
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18 Parameters:
19 map=string
20 Vector map to edit the attribute table for
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22 layer=integer
23 Layer to which the table to be changed is connected
24 Default: 1
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26 column=string
27 Column to update
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29 value=string
30 Value to update the column with (varchar values have to be in sin‐
31 gle quotes, e.g. 'grass')
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33 qcolumn=string
34 Column to query
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36 where=string
37 WHERE conditions for update, without 'where' keyword (e.g. cat=1 or
38 col1/col2>1)
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41 v.db.update allows to assign a new value to a column in the attribute
42 table connected to a given map. Alternatively, values can be copied
43 from another column in the table.
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46 v.db.update is just a front-end to db.execute to allow easier usage.
47 For complex SQL UPDATE statements, db.execute should be used.
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50 Spearfish: adding new column, inserting selectively a specified value:
51 g.copy vect=fields,myfields
52 v.db.addcol myfields col="polynum integer"
53 v.db.update myfields col=polynum val=42 where="label='V. White#1'"
54 v.db.select myfields
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57 Spearfish: adding new column, copying values from other table column
58 with on the fly calculation:
59 g.copy vect=fields,myfields
60 v.db.addcol myfields col="polynum integer"
61 v.db.update myfields col=polynum qcol="cat*2"
62 v.db.select myfields
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65 Type cast (type conversion) of strings to double precision (unsupported
66 by DBF driver):
67 v.db.update mygeodetic_pts col=zval qcol="CAST(z_value AS double preci‐
68 sion)" \
69 where="z_value <> 'N/A'"
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73 db.execute, v.db.addcol, v.db.addtable, v.db.connect, v.db.droptable,
74 v.db.join, v.db.select
75 GRASS SQL interface
76
78 Moritz Lennert (mlennert@club.worldonline.be)
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80 Last changed: $Date: 2007-06-29 09:51:12 +0200 (Fri, 29 Jun 2007) $
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82 Full index
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84 © 2003-2008 GRASS Development Team
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88GRASS 6.3.0 v.db.update(1)