[GRASS-user] Why v.extract produces columns of type "CHARACTER"?

[Glynn Clements]

Nikos Alexandris wrote:

> > The columns produces by v.extract are of type "CHARACTER" and v.dissolve
> > does not like this. It's an "old" issue. Can someone explain why it
> > becomes CHARACTER since grass' type for strings is "varchar"?
> > 
> > Regards, Nikos
> 
> Sorry, wrong question - false alarm.
> 
> Actually, the *real* question I have asked in the past but never really
> got a reply is: why "sqlitebrowser" reports the columns as "varchar"
> while db.describe reports (in grass-shell) the same columns to be of
> type "CHARACTER"?

GRASS' DBMI doesn't distinguish CHARACTER from CHARACTER VARYING (aka
VARCHAR); the constant DB_SQL_TYPE_CHARACTER is used for both
(although there is also DB_SQL_TYPE_TEXT for TEXT).

Also, SQLite doesn't really have column types; it assigns types to
individual values rather than to columns. Columns may have a type of
SQLITE_INTEGER, SQLITE_FLOAT, SQLITE_TEXT, SQLITE_BLOB or SQLITE_NULL,
but it doesn't actually require that the values' types conform to the
type.

-- 
Glynn Clements <glynn at gclements.plus.com>