Since databases other than Oracle do not coerce empty strings
-into null, this code has
-different semantics depending on the underlying database (i.e., the
-row that gets inserted may not have null as its column values),
-which defeats the purpose of SQL abstraction.
Therefore, the Database Access API provides a
-database-independent way to represent null (instead of the Oracle-specific idiom
-of the empty string): db_null.
Use it instead of the empty string whenever you want to set a
-column value explicitly to null, e.g.:
-
-set bar [db_null]
-set baz [db_null]
-
-db_dml foo_create {insert into foo(bar, baz) values(:bar, :baz)}
-#
-# sets the values for both the "bar" and "baz" columns to null
-