[gnome-db] How to insert a NULL with V4

[Phil Longstaff <plongstaff rogers com>]

I want to create a GdaSqlStatementInsert structure to insert a row into
a table.  At least one of the values is NULL, which is a GValue with
gtype == GDA_TYPE_NULL (== 0).  When I try to attach the GdaSqlStatement
to a GdaStatement so it can be executed, I get some error messages
related to the NULL values:

* 19:39:34  WARN <GLib-GObject> gtype.c:3337: type id `0' is invalid
* 19:39:34  WARN <GLib-GObject> can't peek value table for type
`<invalid>' which is not currently referenced
* 19:39:34  WARN <GLib-GObject> gvalue.c:96: cannot initialize GValue
with type `(null)', this type has no GTypeValueTable implementation
* 19:39:34  CRIT <GLib-GObject> g_value_copy: assertion `G_IS_VALUE
(src_value)' failed

This happens in gda_sql_expr_copy() when the value is being copied.

I don't know the GValue system well enough to try to fix this.  Is there
an alternative way to insert a NULL?

Phil