Oracle SQL :12 c features:Invisible Columns

Invisible Column
SQL> create table emp4 (col1 number, col2 number invisible);
SQL> desc emp4
 Name    Null?    Type
___________________
 COL1                  NUMBER
  SQL> insert into emp4 values (1);
     1 row created.
SQL> select * from emp4;
  COL1
 ----------
1
SQL> select col1, col2 from emp4;

COL1       COL2
 --------------------
1
SQL> insert into emp4 (col1,col2) values (2,2);
1 row created.
SQL> set colinvisibleon
SQL> desc  emp4
 Name              Null?    Type
 -------------------------------------
 COL1                               NUMBER
COL2 (INVISIBLE)           NUMBER
SQL> create index in_emp4 on emp4(col2);
 Index created.

SQL> ALTER TABLE emp4 MODIFY col2 VISIBLE;