I guess this is an interesting question came to my mind:

Assume that we have a big table of all emplyees, let's say one million record and we actually forgot to implace the gender field in the table. Now we alter the table and do:

SQL> alter table employee
add (gender VARCHAR2(1) NOT NULL);

but the puzzle is I need oracle somehow start thinking and go throught all 1 million records and find out if the employee is man or women ( depends on their first name ) and populate this new feild with M or W.

How it can be a reality and implemented?