[GRASS-dev] How to calculate log() in v.db.update with SQLite backend?

[Helmut Kudrnovsky]

Markus Neteler wrote
> On Sat, Dec 20, 2014 at 5:49 PM, Helmut Kudrnovsky <

> hellik@

> > wrote:
>> Markus Neteler wrote
>>>>
>>>> Works.
>>>
>>> Submitted to trunk in r63238. Please test (tomorrow) also on Windows
>>> if possible (the name will be something like libsqlitefunctions.dll
>>> which you need to provide to v.db.select).
>>
>> any idea where to find/to get libsqlitefunctions.dll for testing?
> 
> Some folks suggest to compile it (one-liner):
> http://stackoverflow.com/a/20984485/452464
> 
> Markus

libsqlitefunctions.dll now self compiled and tested:

-------------------
v.db.update --verbose map=myprecip at user1 layer=1 column=logjuly
query_column=log(jul)
sqliteextra=C:\OSGeo4Wdev\src\sqliteextension\libsqlitefunctions.dll
SQL: "SELECT
load_extension('C:\OSGeo4Wdev\src\sqliteextension\libsqlitefunctions.dll');
UPDATE myprecip SET logjuly=log(jul)"
(Sun Dec 28 10:38:51 2014) Befehl ausgeführt (1 Sek)
------------------- 
v.report map=myprecip at user1 option=coor                                         
cat|station|lat|long|elev|jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec|annual|logjuly|x|y|z
1|310090|35.39917|-80.19944|185.928|110.998|92.456|122.682|84.582|107.696|111.252|132.842|104.902|113.03|90.424|83.82|83.82|1236.98|4.88916045210132|500657.105808135|183600.883438444|0.0
2|310184|35.20139|-83.83861|533.0952|182.118|154.686|177.038|131.572|136.398|140.716|127|139.7|113.03|89.154|135.382|152.908|1678.94|4.84418708645859|169208.722850323|171737.46864344|0.0
[...]
-------------------

nice, seems to work.

should we add a note to the manual where extension-functions.c could be
downloaded (https://www.sqlite.org/contrib) and how it is compiled (on
windows)? or somewhere in the wiki?




-----
best regards
Helmut
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