[GRASS-dev] Misleading help of v.db.add*

[Huidae Cho]

Hi,

I just tried to add a column to an existing attribute table in
PostgreSQL and found a misleading help message.  The help message of
v.db.addcol/v.db.addtable says "types depend on database backend, but
all support VARCHAR(), INT, DOUBLE and DATE".  I'm not so sure if the
postgres driver in GRASS supports the DOUBLE type internally.   However,
since v.db.add* scripts directly run db.execute which calls
db_driver_execute_immediate(), and PostgreSQL only supports DOUBLE
PRECISION and REAL for floating-point numbers, the help message is not
valid at least for PostgreSQL.

If those three data types are supposed to be common data types for all
database backends, v.db.add* scripts need to convert DOUBLE to a
corresponding valid data type based on the database backend.  Otherwise,
IMO, the help message needs to be revised to avoid confusion.

Huidae