from the feature mail:
For databases, there exists a per-database setting which controls
whether forms check for required fields when entering data.

That is, when the user enters a new record, or updates an existing
one, in a form, and leaves a field empty which is bound to a database
column which requires input, then the form runtime would normally
complain that this field needs input. This is the behaviour up to OOo
2.2, and the default in 2.3 unless some macro will be run manually.

Now, there exists a setting named "Form data input checks for required
fields", on the "Special Settings" tab page of the advanced database
properties ("Edit"/"Database"/"Advanced Settings". Yes, we need to
rework the names here.).

When this is checked (the default for all existing and newly created
databases), then the behaviour in forms will be as described above.

If it is not checked, then forms (all forms in this DB, that is) will
not check for required fields. As a consequence, the DB designer can
specify server-side default values for fields, which up to now was
hardly possible since there is not way Base can generically read
server-side default values, thus it always assumed there're none.

The setting is available in all data source types which (potentially)
support write access to their data, which means it does not exist for
Spreadhseet, Text/CSV, and the various read-only flavours of address
books.