[GRASS-user] update column w/ output from bash function

[Helmut Kudrnovsky]

Ken Mankoff wrote
> Hi Stefan,
> 
> Your code didn't seem to work for me, but allowed me to figure out how to
> make it work. This does:
> 
> db.execute sql="UPDATE CTD_2015 SET YMD=date('2015-01-01', +CAST(DOY AS
> text) || ' days');"
> 
> 
> I'm not sure why I can't simplify this to:
> 
> db.execute sql="UPDATE CTD_2015 SET YMD=date('2015-01-01', '+DOY days');"
> 
> But it is OK.
> 
> Thank you for the hint,
> 
>   -k.
> 
> On 2017-01-12 at 21:17, Blumentrath, Stefan <

> Stefan.Blumentrath@

> > wrote:
>> Hi Ken,
>>
>> In SQLite it would look like this:
> 
>> SELECT substr(CAST(date('2015-01-01', +CAST(DOY -1 AS text) || '
>> days') AS text), 6, 2);
>>
>> Or
>>
>> SELECT CAST(ltrim(substr(CAST(date(CAST(2015 AS text) || '-01-01',
>> +CAST(2-1 AS text) || ' days') AS text), 6, 2), '0')as smallint)
>>
>> If you want numeric return.
>>
>> Thus, try:
>>
>> db.select sql="SELECT substr(CAST(date('2015-01-01', +CAST(134 -1 AS
>> text) || ' days') AS text), 6, 2);"
>>
>> To see how it works...
>>
>> Then try something like:
>>
>> v.db.update map=CTD_2015 column=YMD value=
>> substr(CAST(date('2015-01-01', +CAST(DOY -1 AS text) || ' days') AS
>> text), 6, 2)
>>
>> or
>>
>> db.select sql="UPDATE CTD_2015 SET YMD =
>> substr(CAST(date('2015-01-01', +CAST(134 -1 AS text) || ' days') AS
>> text), 6, 2);"
>>
>> Cheers
>> Stefan
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Would you mind to add some notes regarding date conversion to the wiki?

https://grasswiki.osgeo.org/wiki/GRASS-Wiki



-----
best regards
Helmut
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