AllowNullsEnum

Applies to: Access 2013, Office 2013

Specifies whether records with null values are indexed.

Constant	Value	Description
adIndexNullsAllow	0	The index does allow entries in which the key columns are null. If a null value is entered in a key column, the entry is inserted into the index.
adIndexNullsDisallow	1	Default. The index does not allow entries in which the key columns are null. If a null value is entered in a key column, an error will occur.
adIndexNullsIgnore	2	The index does not insert entries containing null keys. If a null value is entered in a key column, the entry is ignored and no error occurs.
adIndexNullsIgnoreAny	4	The index does not insert entries where some key column has a null value. For an index having a multi-column key, if a null value is entered in some column, the entry is ignored and no error occurs.