Myth: Oracle Cannot Index NULL
The source of this myth is rather easy to understand when you look at the correctly expressed statement:
The Oracle database does not include rows into an index if all indexed columns are
The difference between the myth and the reality is small—it seems that the myth is a sloppy form of the truth.
The truth is that
NULL can be indexed by adding another not nullable column to the index:
CREATE INDEX with_null ON table_name (nullable_column, '1');
Read Section 6.1 for the full story.