How To Refresh Data Dictionary in Oracle?
Your dropped table is in the recycle bin.
Your original constraint names aren't visible - you can't see the primary key name any more (in that view; you can retrieve it from user_recyclebin) - but the constraint is still available internally so it can be restored quickly if you restore the table with flashback table hr.admin_emp to before drop.
The objects that appear in the data dictionary view as BIN$... will only disappear when you purge the recycle bin. But once you do that, they are gone for ever, and you cannot restore them without restoring the whole database, so only do that when you're really sure you don't want them any more.
You cannot, should not, and must not attempt to manually update any data dictionary object, or anything else that Oracle manages internally.
To remove all dropped objects from the recyclebin (current user):
PURGE RECYCLEBIN;To remove all dropped objects from the recyclebin (system wide):
PURGE DBA_RECYCLEBIN;Tables can also be droped without sending them to the recyclebin. Example:
DROP TABLE t1 PURGE;