What are Oracle hidden fields?

Question

ALL_TAB_COLS differs from ALL_TAB_COLUMNS in that hidden columns are not filtered out.

What are hidden fields?

This view differs from \"ALL_TA

Answer 1

Oracle uses them internally (see http://download.oracle.com/docs/cd/B10501_01/appdev.920/a96594/adobjadv.htm) AND you can define such columns for your own tables... when accessed without proper authorization they display NULL instead of the real value (see http://www.techrepublic.com/article/hide-sensitive-data-with-oracle-10g-column-masking)...