Use Oracle and Triggers to Secure Table Data

First, create a table that holds the table name. Say you create a table called SafeTable with a column names SafeTableName and the datatype varchar2. Populate this table with the table names that should not be dropped. Then go ahead and create the trigger as follows:

CREATE or REPLACE TRIGGER checkForSafeTable 
BEFORE DROP ON DATABASE
DECLARE
  TABLENAME CHAR(20);
BEGIN
  SELECT SafeTableName INOT TABLENAME from SafeTable 
  WHERE UPPER(TABLENAME)=ora_dict_obj_name;
  IF sql%found THEN
    RAISE_APPLICATION_ERROR(-20001,'This is a SAFE table');
  END IF;
EXCEPTION
  WHEN no_data_found 
  THEN dbms_output.put_line('This table will be dropped');
END;