[GRASS-user] POW() in SQLite?

[Hamish]

> Hamish wrote:
> > I am trying to use POW(x,n) with SQLite but it fails:
...
> > no such function: POW

Glynn:
> Nope; not in SQLite:
>     http://www.sqlite.org/lang_corefunc.html
> 
..
> > Similar problem if I try x^n:
> > unrecognized token: "^"
> 
> SQLite doesn't have a power operator:
>     http://www.sqlite.org/lang_expr.html#binaryops


 
> > this random webhit suggests that it should be possible:
> >   http://osdir.com/ml/sqlite-users/2009-03/msg00248.html
> 
> That says:
..
> Note: "in addition to the SQLite default". IOW, those
> functions are added by SQLiteSpy, and are not part of SQLite.

ah, skimming error.


Rich:
> I'd manipulate those values first, then pass them to SQLite.


solution:

#no good:
#v.db.update basemap column=volume value="POW(length,3)" --verbose

#good:
v.db.select basemap column=cat,length | awk -F'|' \
  '{printf("UPDATE basemap SET volume=%f WHERE cat=%d;\n", $2^3, $1)}' \
  | db.execute



thanks,
Hamish