sql(1) - f7

1sql(1)                        Grass User's Manual                       sql(1)
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SQL support in GRASS GIS

6       GRASS  can  use  various RDBMS and embedded databases.  SQL queries are
7       directly passed to the underlying database system.   The  set  of  sup‐
8       ported SQL commands depends on the RDMBS and driver selected.
9

Drivers

11       The  list of available drivers can vary in various binary distributions
12       of GRASS.
13
14       | dbfDBF files. Data are stored in DBF files.   |  http://shapelib.map‐
15       tools.org/dbf_api.html    |    sqliteSQLite   embedded   database.    |
16       http://sqlite.org/ | pgPostgreSQL RDBMS.   |  http://postgresql.org/  |
17       mysqlMySQL  RDBMS.  | http://mysql.org/ | mesqlMySQL embedded database.
18       | http://mysql.org/  |  odbcUnixODBC.  (PostgreSQL,  Oracle,  etc.)   |
19       http://www.unixodbc.org/
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NOTES

22                      SQL does not support '.' (dots) in table names.
23
24                      Supported table name characters are only:
25                     [A-Za-z][A-Za-z0-9_]*
26
27                      A table name must start with a character, not a number.
28
29                      Text-string  matching requires the text part to be 'sin‐
30                     gle quoted'.  When run from  the  command  line  multiple
31                     queries should be contained in "double quotes". e.g.
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33                     d.vect map where="individual='juvenile' and area='beach'"
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35
36                      An  error  message such as "dbmi: Protocol error" either
37                     indicates an invalid column name or an unsupported column
38                     type (then the GRASS SQL parser needs to be extended).
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40                      DBF  column  names are limited to 10 characters (DBF API
41                     definition)
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EXAMPLES

44       Display all vector points except for LAMAR valley and  extensive  trap‐
45       ping (brackets are superfluous in this example):
46       d.vect  trapping_sites_points  fcol=black  icon=basic/diamond col=white
47       size=13 \
48           where="valley <> 'LAMAR' OR (valley =  'LAMAR'  AND  description  =
49       'extensive trapping')"
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51
52       Select  all  attributes from table where str1 column values are not 'No
53       Name':
54       echo "SELECT * FROM archsites WHERE str1 <> 'No Name'" | db.select
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57       Example of subquery expressions from a list  (does  not  work  for  DBF
58       driver):
59       v.db.select mysites where="id IN ('P04', 'P05')"
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61
62       Example of pattern matching (does not work for DBF driver):
63       # match exactly number of characters (here: 2):
64       v.db.select mysites where="id LIKE 'P__'"
65       #define wildcard:
66       v.db.select mysites where="id LIKE 'P%'"
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68
69       Example of null handling:
70       v.db.addcol map=roads col="nulltest int"
71       v.db.update map=roads col=nulltest value=1 where="cat > 2"
72       d.vect roads where="nulltest is null"
73       v.db.update map=roads col=nulltest value=2 where="cat <= 2"
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75
76       Examples of complex expressions in updates (using v.db.* modules):
77       v.db.addcol map=roads col="exprtest double precision"
78       v.db.update map=roads col=exprtest value=cat/nulltest
79       v.db.update map=roads col=exprtest value=cat/nulltest+cat where=cat=1
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81
82       Examples of complex expressions in updates (using db.* modules):
83       echo "UPDATE roads SET exprtest=null"
84       echo "UPDATE roads SET exprtest=cat/2" | db.execute
85       echo "UPDATE roads SET exprtest=cat/2+cat/3" | db.execute
86       echo "UPDATE roads SET exprtest=NULL WHERE cat>2" | db.execute
87       echo "UPDATE roads SET exprtest=cat/3*(cat+1) WHERE exprtest IS NULL" |
88       db.execute"
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91       Instead of creating and updating new columns with  an  expression,  you
92       can use the expression directly in a command:
93       d.vect roads where="(cat/3*(cat+1))>8"
94       d.vect roads where="cat>exprtest"
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SQL support in GRASS GIS

Drivers

NOTES

EXAMPLES

SEE ALSO